What is your operating system? Is the screen just black or does it have a message? In the regedit export, did you try exporting one high-level key at a time (HKCL, HKLM, HKCU, HKUS, HKCC)?
I don't know of a quicker way.
After you do that, if you don't come up with a way to fix the problem, you might try jv16PT Registry Compactor.
It gives you a window showing 11 registry hives.
Click on
If it completes, ignore the "Please restart your computer" message and repeat with another hive.
If you get a black screen, reboot and continue until you have done all the hives, then reboot.
This won't fix anything, but you will know which hives are impacted.
If you're lucky, the damage will only affect hives belonging to your userid. You might then be able to create a new Admin userid, reboot, then logon with the new id. You will lose your desktop customization and some programs will need to have your personal settings redefined. You may have to retailor the Start Menu. I'm assuming your OS is XP.
