Boot the WD Data Lifeguard diagnostics DOS CD to run an extended scan on the HD:
Hard Drive Diagnostics Tools and Utilities (Storage) - TACKtech Corp
See if your HD can be seen using Diskpart,
Partition - Mark as Active (Method Two)
You can see a picture of your HD's partitioning and mark Active using free Partition Wizard bootable CD which also has a HD Surface Scan and can Check File System (both are needed to ascertain HD stability). Once 100mb or Windows 7 is marked Active, click on HD to highlight it, then from Disk tab select Rebuild MBR, Apply, reboot. This may preclude the need to run Startup Repair 3 times.