you can use your windows installation disk, or recovery partition to run a chkdsk on your c:\ partition. Usually its like this:
chkdsk /x /f c:
/x dismounts the volume and /f means automatically fix the file system.
Also you may want to run a diagnostic on your hard drive, as sometimes this error can happen if the hard drive is failing. But usually improper shutdowns will start corrupting the file system.