Just ran across this... and it's bad for players of high stakes on PokerStars...(and though it doesn't say so, since it's allegedly happening at Poker Stars, if it really turns out to be happening, then I believe it can happen elsewhere.)

And the crazy thing is that more than a few times, I have been disconnected right at a crucial point and lose the pot, or be blinded out before I can get back to the game. And the only times it has ever happened to me was when I was in a pot with one other person.
I have wondered if this was possible, though at the stakes I play, why would anyone bother... but then again, maybe the poor fool was broke and had to start over...lol...

Account Under Investigation in Alleged Forced Disconnection Attack on PokerStars | Pokerfuse Online Poker News