I discovered something. I was going to reformat, so I through in the boot disk. I told it to boot with DVD-Rom capabilities. It told me that no drive was detected. Up until today, I was always able to boot from a disk. It seems kind of strange that my DVD-Rom would suddenly go bad. I don't think this is what happened.
Yesterday, after I'd done a clean install of the system, I needed to pull out the drive just far enough so that I could see the model number so I'd know which driver to get. This is the only possible way I can imagine that anything happened to the drive. Even so, this seems unlikely. I only pulled it out about half way.
Do you have any ideas now?