Thanks for the replies so far folks. The thing I notice most is that there really is no catalyst that starts this, not a bad beat or anything, but I always manage to be an idiot. I feel like I get over aggresive post flop after a while, but I don't really know how it compares to my play early on... I just know that sometimes I will 3 bet people trying to get them off a hand when I know they wont budge. Then I started getting nervous and soon enough I've lost everything. I know you were being honest with me, which is something I certainly need to be with myself, but I when I'm playing my game, I just don't seem to lose money. Variance could be a possibility if this had only happened once or twice, but it has really happened about 10 times in the past year.

I have thought about depositing quite a bit more (500BB) next time, but it worries me that I will continue my trend and end up losing much more. When I'm at my local B&M, I also seem to have the same trends, that is, I'll be up 40 BB after 2-3 hours and then lose it all back in the next 3-4 hours. I guess for right now I need to just quit when I'm ahead until I can gain the control to quit when my ability to win is over.

EDIT: Let me add that I have about 70k hands logged at Pokerstars and probably anotjher 5k at the local casino.