May I suggest you don't run Driver sweeper. I've seen it cause way more problems than it solves. I've been installing ATI drivers for the best part of a decade and every month I just install the latest drivers over the top of the old ones. Never had a problem doing that.
I always create a system restore point before upgrading video drivers though to be on the safe side.
Rbeldua I've seen Driver sweeper take out systems. I've found if you do need to do a clear out, for example moving from Nvidia to ATI CCleaner seems to be the safer option. Also reinstalling directx after using driver sweeper or ccleaner is also a good idea IMHO.
EDIT: What temp. is your card when this happens?