I recommend that you run a checkdisk on your system.
1: Open My Computer, and then select the local disk you want to check.
2: On the File menu, click Properties.
3: On the Tools tab, under Error-checking, click Check Now.
4: Under Check disk options, select the Scan for and attempt recovery of bad sectors check box.
To open My Computer, click Start, and then click My Computer.
All files must be closed for this process to run. If the volume is currently in use, a message box will appear prompting you to indicate whether or not you want to reschedule the disk checking for the next time you restart your system. Then, the next time you restart your system, disk checking will run. Your volume will not be available to perform other tasks while this process is running.