Help!!!!Trojan Horse

[creek6170]

I have a trojan horse virus on my System files and temp folder. I can't delete it or move it to chest. I have tried everything. The file that it says the virus is in in my folders don't show up. Can anyone help me get rid of these viruses. one of them  is Win32:Trojano-1941 [Trj] it is located in C:\WINDOWS\system32\st3.dll.

[FreewheelinFrank]

st3.dll may be part of Look2Me- try these removal tools:

http://forum.avast.com/index.php?topic=17647.0

Also worth running is Ewido anti-Trojan Program:

http://www.ewido.net/en/

[DavidR]

This may also be because the file is in use, its location in one of the system folders, windows protects from deletion or movement. You can schedule a boot-time scan from within avast, so windows can't protect them because it isn't running.

However, as FWF mentions it could be a part of a more persistant trojan.

[FreewheelinFrank]

It may also be because the infected .dll is injected into Windows processes. Ewido can deal with these process injecting Trojans by killing the infection in memory, but I suspect the problem for avast! might be that these Windows processes are infected even during a boot time scan. Certainly avast! doesn't seem to be able to remove this type of infection, although nobody from the avast! team has confirmed or denied my suspicions.