I had the same problem and couldn't download any files to clean it up. Used a separate computer and found the following keys--to enter into the manual registration window. The second one "removed" the malware--sufficient to let me download tools that completely removed it.
XP Internet Security 2012 / XP Security Center 2012 / XP Antispyware 2012 / XP Antivirus 2012 / XP Security 2012 / XP Home Security 2012 all these are same spayware.
If you are trying to remove this spyware, there are full instructions on how to do that manually at the link :Message was edited by: Ex_Brit on 29/12/11 7:00:46 EST AM
How to fix file associations in Windows: https://community.mcafee.com/docs/DOC-1264
Kuttus please don't post registry key fixes, especially from rival software companies.