Okay... two things... WITH THE SYSTEM OFF...
1. Disconnect all usb peripherals at this point.
2. Carefully remove the ribbon cable from the hard drive.
3. Check for bent pins. (Very carefully straighten them if needed).
4. Slide the ribbon cable back onto the drive.
Sometimes a poor connection at the drive can cause this problem.
A little oxidation may accumulate overtime.
Just removing and reinstalling the cable may be enough to restore the connect.
Let me know if this works, or if we need to do more.
If you can boot now, then after windows has started, reconnect your usb peripherals.
Caution, with usb peripherals, if you are powering them from the usb ports of your computer, you may be underpowered. It is always best to have your peripherals self-powered.