got this message from Avast: Win32:Delf-DOM [Trj]

I have gotten this message last night, and after I got this message I even cannot open www.avast.com or other anti-virus website. Everytime I open thess websites, it is closed automatically.
A virus has been detected.
File Name: C:\WINDOWS\system32\d3acdb.dll[UPX]
Malware name: Win32:Delf-DOM [Trj]
Malware type: Trojan Horse
VPS version: 000718-0, 02/27/2007
???
Recommended Action: Move to Chest

I have tried numerous times to delete the file. It is done successfully each time but the file reappears together with the virus. Can anyone explain to me what is going on and how to get rid of this? Thanks!

Hi radish,

Maybe this thread would be useful:

http://forum.avast.com/index.php?topic=26864.0