I get dropped in probably every second game I play on SC. Do you know why? I don't have lag, and everything seems, fine, until I get the countdown box.
(Blizzard is No help)

Drophacks.

Nope, Its too often for that. Its almost every game.

You must be reaaaaaly nasty on SC .

Well, mind giving us more info? I don't think this is 'supposed' to happen no matter what, so its probably some side-effect of something else. Does your internet sometimes turn off? Do you use a wireless USB adapter? If so, is it snug as a bug? Do you disconnect from bnet after dropping from the game? Any other processes on? Is someone else using teh internetz? Stuff like that. When I had this problem (WoW and WCIII) it was because my wireless USB adapter was crapping out. I disconnected from the internet all the time, and had to take out and put back in (and perform a ritual of turning off/on all six network processes... Creepily enough, it worked...) to get it to work for a set amount of time.. it was pretty nasty.