Run "chkdsk /r" on the drive (type this into the Run dialogue or a command prompt window)
If the system is unbootable, use your Win7 / Vista disk to boot the PC and run repair my computer.
Sometimes this STOP error is related to either a low CMOS battery or simply having to take it out and put it back in.
check device manager for any non functional hardware
(right click my computer -> manage -> device manager)
Check your windows update history for any new or updated drivers. if you installed any new drivers, uninstall them. If you updated any drivers, right click on the device in Device Manager -> Select Properties -> Select Driver tab -> Roll Back Driver