Start and then to Run
Type in Chkdsk /r Note the space between k and /
Click Enter ...It will probably ask if you want to do this on the next reboot...click Y
If the window doesn't shutdown on its own then reboot the system manually. On reboot the system will start the chkdsk operation
This one will take longer then chkdsk /f
Note... there are 5 stages...
It may appear to hang at a certain percent for a hour or more or even back up and go over the same area...this is normal...
DO NOT SHUT YOUR COMPUTER DOWN WHILE CHKDSK IS RUNNING OR YOU CAN HAVE SEVERE PROBLEMS
This can take several hours to complete.
When completed it will boot the system back into windows.
Let me know if this fixes the problem
Have you done the HD diagnostics as datarunner suggested earlier?