Are you running the original OEM installation? Sounds to me like it could be a bad install. You've removed all the crapware right?
If you can find the time, then I highly suggest you do a clean install Clean Reinstall - Factory OEM
. I do this with every new computer and have never had a problem
EDIT: Just read that you already tried a clean install. In that case, it sounds like this could be a bigger problem than I thought.