I have been recieving the NT System Authority Shutdown error because of an RPC Failiure. First I thought it was Blaster, but I was running SP2 and always had a firewall going, (I use NVIDIA firewall.) Then I did some searching and found out about Sasser and how it could do the same thing. I downloaded, Stinger, AVG and used the free virus detect at symantec.com and antivirus.com as well as Windows Malicious Software Removal Tool (god, did they have to make that huge name for it?) They all were running current virus definitions and they found nothing. Nada. The crash primarily occurs when I start a new process that is an internet application. AOL, IE, Firefox, etc. So I am thinking it is some sort of virus. I checked the firewall log this morning, and it has been blocking traffic from 192.168.0.1:1900 UDP (my D-Link router address) to 18.104.22.168:1900 UDP (the upper end of the open UDP range) There are some 100000 instances of port blocking at that address, and I don't know if that is the problem or not, or if it is just routine blocking. What else could cause an RPC Failiure besides those two viruses and the multitudes of variants? I appreciate your input. There is another thread here in this forum about this, http://www.techspot.com/vb/archive/index/t-8147.html but it degenerated into a talk about blaster and sasser. Anyway, Help!