Well, as you have an install disk, boot up with that - if you are presented with an inverse window with Windows Setup (EMS Enabled) - press enter and when you get to the splash screen select Repair your Computer to navigate to the Recovery Environment and select Command Prompt.
Enter bcdedit |find "osdevice" and using the partition letter that gives, enter (assuming C ) -
sfc /scannow /offbootdir=C:\ /offwindir=C:\Windows
exit (when complete to close the cmd window)
Remove the disk then Restart.
That's a Pipe symbol before find (uppercase of \ ) and there's a space before each forward slash.
I'm sure you can spare ~15 - 20mins for that.