XP reactivation error

Good Morning,
I turned on the computer and at the login screen received a message that there was an error in the registry but it had been corrected. I typed my password and received the message that "because of significant changes that had been made I must reactivate windows now". Strange because I have made NO harware or software changes in months. I selected yes to reactivate, the screen flashed to the desktop and went back to the login in screen with the instruction in the lower left corner of the screen to turn off computer now. I cannot get passed this. The system will not allow me to get any further. I have tried booting in safe mode but this does not work either.
To say that I am perturbed would be the understatement of the month. Any help short of reformatting would be most appreciated.
Thanks.

 

http://support.microsoft.com/kb/314935/en-us

Or call the support number and have them troubleshoot it. USA, MS Product phone number 1-888-571-2048

 

Thanks for the response. I was able to boot in safe mode. This allowed me to get into the event viewer. Numerous drivers are not loading, hence the reason it will not boot(duh). I shut the computer down and rebooted. On the intial boot screen, it shows that I have only 128 mb of ram when in reality there is a one gig stick in there. I beleive that is the root of the problem and will replace with a new ram. Thanks again!