Boot the Windows 7 DVD Repair console or burn and boot a Windows 7 Repair CD: System Repair Disc - Create
Click through to Recovery Tools list to run Startup Repair up to 3 separate times with reboots, which it may need to repair or rewrite the MBR if necessary. Startup Repair - Run 3 Separate Times
Check Disk, System File Checker and most all other tests are automated in Startup Repair.
Run it regardless of whether it finds an OS to repair and offers you a Repair when you boot in.