Overwhelming states of being reached through meditation

One thing to say right off is, this experience you describe is not a head trip and no amount of impressive intellectual bs is likely to help convert this to the fertilizer it can be. It is about mastery of the emotions. Something big is emerging from your own mind and it aint going to be intellectualized away. Ever.

The very well trained and experienced buddhism teacher Alan Wallace addresses "meditative experience" ie "nyam" at length. Sounds to me that is what you are encountering. My own experiences are possibly very relevent too, they are consistent with Alans teaching. Since they can be quite frightening and end up as fragmenting instead of powerfully beneficial it pays to get great guidance to be sure they end up as the unimaginably positive influence they can be.

One important point would be to get qualified guidance from a qualified teacher. Meditation, shamatha practice, when it is working right, will "dredge up the rotting corpses from the mud of the psyche." In fact when it does so it is a sign the practice is working. However its so powerful and fragmenting its necessary to have guidance. Otherwise we can be thrown off, put off, and even have our well being damaged.

I had prior experience from years of training in psychology , psychotherapy and seeking out the most challenging experiences possible for the sake of rapid efficient personal growth. Still I was knocked off my feet by the power and sense of "loss of control", emotionally, when I got the meditation practice working for me.

It takes an intrepid attitude and competent external support to get thru such experiences. My finding was that the "gold", beyond what I was capable if hoping or dreaming of followed immediately that fragmenting moments ....

don't know if its possible to contact posters thru this site ... feel free to if you would like more discussion

You experienced first two jhanas. Being accompanied with happiness. Yes it feels like explosion. And you also experienced the third Jhana which is disturbing. I recommend you to study Jhana meditation This will help you to develop further

It so happened in progressing to higher stage of knowledge. Out of sixteen stage of knowledge regarding insight meditation, in the third stage it used to happen in somebody depending on the past merit. "intense emotional explosion in my chest" and "overwhelming bliss" if you note "know it" repeatedly or if you cannot concentrate any more just remember Arahan (one of the qualities of Buddha) until you can concentrate again. By doing so you can attain higher stage of knowledge. If you dare not do by yourself alone, go to one of the retreat and in front of the meditation master you can try again. Surely there will be no problem.

I'm not equipped to answer this, but I can maybe give you some pointers to people who can, and maybe allay your fears.

Effects such as you are describing have been described in quite some detail by Daniel Ingram, Willoughby Britton (from both a practice and academic/clinical point of view), and others. If you don't get a good answer here (and even if you do), I recommend dharmaoverground.org, especially this sub-forum, where people are willing to offer guidance. Try to get answers specifically from Dan himself, and also Nikolai (there are several on there who seem to know this stuff, but those two do seem to be especially experienced).

Also look for Willoughby's stuff at Cheetah House (she specifically mentions the work difficulties you describe). And look for Dan's podcast interviews on Buddhist Geeks (several years ago now). Willoughby also speaks there. Here's the first of her two part interview.

The bottom line is, from what I read, what you've experienced seems to be not uncommon (some of the dharmaoverground folks seem to think it is inevitable if following a particular practice path, but I can't find broader support for that view), is almost always able to be worked through, but your best bet is to find a good teacher who either has experience of this kind of thing, or has been trained by someone who has.

See also the answer I gave here.

CAVEAT: Don't trust the internet any further than you can kick it -- and that includes dharmaoverground, this SE site, and indeed this post. Always cross reference, triangulate, and always always keep your common sense switched on.

You may have experienced the first Jhana.

Quite withdrawn from sensuality, withdrawn from unskillful mental qualities, he enters and remains in the first jhana: rapture and pleasure born from withdrawal, accompanied by directed thought and evaluation. He permeates and pervades, suffuses and fills this very body with the rapture and pleasure born from withdrawal.

If you master it you will be able to enter and exit it at will. Getting stuck in it is not uncommon. The same goes for choosing to stay in it because it is pleasant, which is seen as a hindrance to final liberation.

Speaking the dhamma or keeping 'noble silence' is also part of the Jhanic experience. This sounds similar to what you described. You struggled to talk about work but once you were able to share your experience you could not stop talking.

Fighting against our lifelong programming, like you described, can make this experience seem negative. If you want to keep trying to master Jhana, while still continuing to work and continuing to fit in nicely with society, I recommend finding a teacher. Otherwise you might continue to experience this state for extended periods while attempting to master it.

First of all, I think your question has gotten worse at explaining your condition through your edits (sorry!).

In Theravada Buddhism, and really I think I speak for all of Buddhism when I say, the object is to understand reality as it is. This means you actually have to understand the experience before you can "fix" it. Actually, it means once you understand the experience, there will be no need to fix it.

Saddhāya tarati oghaṃ appamādena aṇṇavaṃ,
Viriyena dukkhaṃ acceti paññāya parisujjhatīti.

With confidence one crosses the flood, with vigilance the ocean;
With effort one overcomes suffering, with wisdom one is purified.

SN 10.12

So, first you need to purify your understanding. What is it you are exactly experiencing? What is really happening? The Buddha reminded us that understanding reality means breaking experience up into its constituent parts and seeing them just as they are (called Yathā-bhūta-ñāna-dassana). For example, in the Bahiya Sutta (Ud 6):

"diṭṭhe diṭṭhamattaṃ bhavissati, sute sutamattaṃ bhavissati, mute mutamattaṃ bhavissati, viññāte viññātamattaṃ bhavissatī"ti. Evaṃ hi te bāhiya, sikkhitabbaṃ.

"In what is seen, there will be only what is seen; in what is heard, there will be only what is heard, in what is sensed, there will be only what is sensed, in what is thought, there will be only what is thought." Just so indeed should you train, Bahiya.

The Buddha explained that to the extent that Bahiya could train himself in this simple teaching, "tato tvaṃ, bāhiya, na tena" - "therefore, Bahiya, there will arise no 'you' because of that," which means that there would be no misinterpretation of the experience as "me", "mine", etc.

"To the extent," the Buddha continued, "that there arises no self," "tato tvaṃ, bāhiya, na tattha" - "to that extent, Bahiya, there will arise no 'you' in regards to that object." "To that extent," the Buddha concluded, "nevidha na huraṃ na ubhayamantarena. esevanto dukkhassa." - "there will be neither here nor there or anything in between. This indeed is the end of suffering."

So, let's examine what exactly you experienced, based on your words, in order to try and see it for what it is:

I experienced an incredibly intense emotional explosion in my chest

First of all, emotions are not in your chest, they are mental. What you experience in your chest is a physical symptom, maybe accompanying emotion, maybe not. It should be understood as it is (in our tradition, this means reminding yourself "feeling, feeling..." until it goes away).

Second, "incredibly intense" is a judgement - not bad in itself, but indicative of some emotional reaction to the experience. That too should be seen as it is ("disliking" or "upset", for example).

I experienced what can only be described as immediate and overwhelming bliss.

Bliss is either mental or physical (or both); either way, it is a feeling (vedana) and should be understood as it is ("happy, happy" or even "feeling, feeling")

My meditations were shorter, but extremely powerful (and actually became the highlights of my day).

This indicates some degree of attachment, which is a cause for addiction and should be understood as it is to stop it from escalating ("liking, liking").

I felt as if my ego wasn't quite ready to deal with the complexities of modern life, and rather than help my daily existence, this new state of mind became a hindrance.

This as well is a judgement, probably indicative of aversion. Even though a state may be objectively "bad", disliking just aggravates the condition. This should understood as it is ("disliking, disliking").

Talking to my clients on the phone, fielding their complicated questions, suddenly became a daunting task. And the part of my brain that allowed me to program websites (which is what I do for a living) was struggling to focus.

Sometimes struggling to focus on worldly things simply means you are unable to care about what has no intrinsic benefit; you may have to in that case force yourself to stop practicing in order to carry out the worldly duties as you see fit. In this case, though, it sounds like you probably have too much concentration and not enough effort. If the mind is unwieldy, inflexible, it will have trouble keeping up with reality and thus interacting with daily life. Insight meditation that focuses on mundane reality should help. If you truly are distracted (in the sense of the mind flitting to many different objects at once), then it probably has less to do with the meditation practice and more to do with your reactions to it that have led to anxiety, etc.

It was worrying.

States can't be worrying, you can just worry about them. Which is unwholesome and should be understood as it is to avoid escalating it ("worried, worried").

I didn't feel as though I was in control of these feelings, or sometimes, even myself (I remember one time talking to a friend about these new experiences, and being unable to stop myself from talking -- I literally kept interrupting him with my "insights", very unlike me).

Welcome to the world of non-self :) The Buddha said that aspects of experience are non-self, including nibbana. We simply fool ourselves into thinking we are in control, when in fact the most we can do is react (or not react, which would be better).

Interrupting your friend, on the other hand, is a sign of too much energy - probably accompanied by faith, and, as you say, insight. Energy, faith and insight can all become hindrances or imperfections of insight (vipassanupakkilesa) if you follow them without being self-aware and letting them go. It is important not to cling to any positive states that may arise; as you have learned, they can lead to problems in your daily life.

Hopefully this at least gives you some guide as to how you can better pinpoint what exactly you experienced; if you want help, you will need to be able to express what is happening on a momentary experiential basis; the present moment is just one moment, and it is the only moment that is of true importance:

Let one not go back to the past, nor worry about the future, for the past is gone and the future unreached; but which phenomena arise here and now, let one see clearly into them all.

This is unconquerable, this is unshakeable; knowing thus, let one so devote oneself. Today, indeed, should one strive at the task; who knows whether death comes tomorrow? There is no bargain to be made with him, Death with his great army, But one who dwells thus ardently, day and night untiringly, is said by the peaceful sage to have had a blessed night.

-- The Buddha (MN 131)