Bagel Worm

[irvdk]

I have a question regarding Avast Free Home Edition.  I was working on a machine for my brother-in-law that had Norton on it. I knew it was infected so I went to Kaspersky and Nod32 online scanners.  I then un-installed Nortons and installed the latest version of Avast with updates. The worm was called Win32.exe openopen.  Also known as emailworm win32 or bagel.gen.  Avast would not find it although I could see the files win32.exe open, win32.exe openopen, win32.exe openopenopen.  I could see the files in the registry also.
this is an old virus and I do ot understand why it did not find it.
Could someone help me to understand?
Thanks in advance,
Irv

[DavidR]

There is a possibility that there are remnants of NAV still on your system, if avast finds these it may not install fully to avoid conflict. However, a warning message is usually displayed.

Another link worth looking at which is a program removal tool, which can remove the remnants of a number of different Norton Programs:
Removing your Norton program using SymNRT

Run the Norton tool, reboot, uninstall avast, reboot, install, reboot.