Black Screen After Windows Boot Screen

Self-built XP machine, approx 4 yrs old.
1.6 gig processor, 1 gig RAM.
NVidia 5200 graphics card, onboard sound

Machine was working fine a few hours ago, BSoD came up, error message was too quickly dumped to read. Since then, machine will not boot except in Safe Mode.

Things tried:
1. Reseating memory and various cards
2. Resetting drivers and video settings
3. Disconnecting unnecessary hardware
4. MSconfig adjustments to boot only required items.
5. Swapping video card
6. Restoring from last save point (yesterday)

So far, nothing has worked. Help?