The SFC /SCANNOW Command - System File Checker scans the integrity of all protected Windows 7 system files and replaces incorrect corrupted, changed/modified, or damaged versions with the correct versions if possible. If you have modified your system files as in theming explorer/system files, running sfc /scannow will revert the system files to it's default state.
Run this on your Hard Drive(s). This will show you how to run Check Disk or chkdsk in Windows 7 to check a selected hard disk for file system errors and bad sectors on it. With both boxes checked for all HDDs and with Automatically fix file system errors. Post back your logs for the checks after finding them using http://www.sevenforums.com/tutorials/96938-check-disk-chkdsk-read-event-viewer-log.html
Pay close attention to Part 3 of the tutorial "If you have errors". Take the test for at least 7-10 passes. It may take up to 22 passes to find problems.