Friend had a PC with a horrible ass virus, not sure what it was though because I picked up this "project" half way through. Tried to install XP Professional via USB, clean format and all, supposedly it worked until the install made the computer restart, then when it would get to the BIOS, it would sit and do nothing. The floppy drive light was constantly on (lol floppy drive), so I tried getting in the F11 boot menu; says that it's going but never loads. Same with F2 setup. Took it apart and unplugged the floppy drive, restarted, and same thing. Tried a boot CD but for some reason the CD drive will not open. Lights flash when you push the button, but it never opens. I was probably going to reset the CMOS but before I do that I figured I'd ask you guys.
i've had floppy drives hanging up the boot when the cable was on backwards, but that doesn't sound like your problem since you disconnected it. Reset cmos i'd say.
reset the cmos, if that doesn't fix it strip the system to the bare minimum of components. Adding them back one at a time as you test.