Oh, No, Not Again

My laptop computer is once again refusing to boot after POST. It's exactly the same problem as happened with the other computer and with other hard drives. Even after completely reinstalling Windows, you can end up with this happening. It passes POST, but then stops at the blank screen with the flashing cursor. (You see that screen briefly during a normal boot.)

If it's anything like the last time this happened -- on another laptop and using a different physical hard drive -- I'll be able to attach the drive to another properly booting computer and get all of my files off of it. Fingers crossed that I can somehow get through this without having to reinstall Windows from scratch once again, but I'm not confident.

I just wish I could understand what causes my computers to do this. Dell has even gone as far as to replace the motherboard in one of them. There's no logic to when the failure happens!