Thanks for all the replies so far. I think I've narrowed down the problem a little bit. I tried all the suggestions above and none of them worked for me, so I got tired of this and just reformatted my computer. It worked fine for a day after I updated all my drivers
, but then the problems came back again.
I've managed to fix the alt tab problem by changing back to the xp look when it alt tabs, but the thumbnail preview flashing (causing me to not be able to click on the minimized icons on the taskbar) and the mpc volume sliding is still there. I ran selective boot with all the services disabled, and all these problems went away.
Is there any clue which service would be causing these problems?
And I forgot to mention, the mpc sliding problem only happens when I'm actually select mpc. If I run it and click on somewhere else the volume won't move. It's only when its selected that it does this.