Can't restore system after installing Internet Security 2010

Hi, I recently installed Norton Internet Security on a pc using XP.  After installing the computer ran extremely slow and I removed Registry Defender, a known malware and a lot of other stuff.  The computer continued to be slow and I tried to do a System Restore in both normal and Safe mode.  After rebooting I always got the message that the Restore did not work.  I've read several articles saying that Product Tamper Protection must be turned off for System Restore to work.  I tried this and still could not do the System Restore.  These articles were for 2009 and I've seen nothing about 2010 on this issue.  I'd appreciate any suggestions on this matter.

Regards,

123steve