"windows has detected a registry/configuration error. Use SCANREG..."

Hello,
I have a Dell Dimension 8100, Windows ME...

I went on vacation for about 2 days and came back. Turned on the computer and for some reason it gave me the message:
(it can't go on normal mode, but safe mode...)

"windows has detected a registry/configuration error.
use SCANREG to correct this error."

...and that i'm supposed to go on safe mode. So when i go on safe mode, the computer just freezes on the greyish white screen. Is this a common problem?
I am basically stuck there...i really hope reformatting my computer is not the choice. Could it be a virus?
* It also said something about 'new hardware installed' but i'm pretty sure i did not install anything....

Please help, your help will most definitely be appreciated!

Thanks,
Leonard