There are several options to avoid the system shutdown:
Go to Start->Control Panel->Administrative Tools->Services->Remote Procedure Call (RPC)->Recovery Tab and choosing "Take No Action" for all three choices.
Go to Start->Run, type in shutdown/a, and press Enter.
Change the system time back by several hours.
Disconnect from the Internet.
DOWNLOAD THE ANTIVIRUS FOR BLASTER HERE
http://securityresponse.symantec.com...r/FixBlast.exe