Can you run a chkdsk:x /f/r, where X is the OS drive/partition. Reboot and let it do it's thing.
Also, run a disk clean up and a defrag. If that does not work:
You could do a repair-install of the OS - launch the OS installation, then select to repair an existing installation. You will lose the OS updates, but not the programs you have installed. You'll need the OS install media and of course the OS key.