svchost.exe problem

I’m running Avast business on a Windows 7 computer. For about the last week, at startup and then sometimes several times during a session, Avast reports that a certain website (it’s always different) has been blocked and that c:\windows\system 32\svchost.exe is where it is happening. I do not have to be running a browser for this to happen.

I did some research and learned that there is an svchost.exe trojan around, and ran Roguekiller, adwcleaner and an Avast full system scan to find it. Nothing. I’m still getting the message from Avast.

Advice?

Read the sticky at the top of this forum and follow the instructions.