Using Catalyst drivers 11.02 with a 4870x2 if you scroll to the very right of the screen then scroll directly up the game frames jump, smoothness while scrolling is lost.
It doesn't matter what video settings are set, all are effected, including having reduce mouse lag on or off.
Is a thread about it here (some guy using an even older set of drivers).
Forgot to add, if you scroll to the left+up, left+down, or right+down the scrolling remains smooth.. The glitch only happens if you scroll directly right+up.
edit2: lol.. well doing some research seems many people are suffering this across a large amount of games, so it isn't the sc2 engine causing this problem. guess i'll just roll back drivers... be nice if you could tell ATI to hurry up and fix the issue, I'm sure more blizzgamers soon will suffer this same problem not knowing what caused it.