Black Screen with typing cursor only

I have been given a computer to fix and I have never seen this issue. When booting the computer, it loads the BIOS and does its post and then goes to a black screen with a typing cursor. When I try to type ctrl-alt-del it just restarts. I am trying not to have to reinstall any operating system (1: since I have no idea what is on it, could be Windows XP or Windows Vista or Windows 7, 2: want to try and save information). I can't use a recovery disk cause I don't know what OS either. Not yet at least. This showed up on my desk this morning when I got in.