NIS 2009 infected and will not remove

Hi ,

 

I am using NIS 2009 (16.7) fully updated on XP Sp3.

 

Today my son downloaded something and executed it ........and from that point my PC is completely infected.

 

NIS doesn't detect it and Malwarebytes detects it .........but fails to remove (it asks me to reboot but system remains infected)

 

My task manager , regedit , msconfig , folder options are completely disabled each drive has' Run in Safe Mode ' option when right clicked followed by an Autoplay option.

 

Please help me !!!!!!!!!!! 

 

[edit: Changed subject for clarity.]

Message Edited by shannons on 08-20-2009 12:31 PM