Before doing a repair install you could try running chkdsk
on the drive. Download this file:http://www.thecomputerparamedic.com/files/rc.iso
and then burn it to a CD as an ISO. Insert the CD into the CD drive, and then restart the computer. Click to select any options that are required to start the computer from the CD drive if you are prompted. When you are prompted, type the Administrator password. If the administrator password is blank, just press ENTER.
Type: chkdsk /r
It's important to have a space before the "/".
To exit the Recovery Console and restart the computer, type exit
at the command prompt, and then press ENTER.