Do this
1. Start , run, cmd, chkdsk /f (make sure C:\ is selected)
Press yes to have it done on restart. then Restart. After it completes go to 2.
2. Start , programs, accessories, system tools, disk defragmentor Defrag the entire volume.
3. start, run, msconfig (tab over to startup, and remove programs that you dont *NEED* starting right away)