I recently had this error and I know that there is probably a thread around here somewhere with it and I don't know that it's fixed yet, but what I do to avoid it is stay out of my inventory as much as possible when not selling things. I also don't stay in my hero list very long (these are both areas I've had it kick me out with error 3007). Apparently selling things doesn't seem to affect it, but I can't say that for sure.

I know I'm not a tech guy for diablo 3, but I figured that this might help a few people to still play the game. I haven't had another error since this morning, so either they fixed the problem or I'm avoiding it.

See you all in D3!!!