I searched registry for aswcmnb and got nothing.
I started DrWatson and then tried to start Avast, got the error as expected but now it had a details button. The diagnosis was as follows :
High level portable functions performed an invalid memory access.
Module Name: ASWCMNB.DLL
Description: High level portable functions
Version: 4, 1, 389, 0
Product: avast! Antivirus
Manufacturer: ALWIL Software
Application Name: Ashavast.exe
Description: Splash screen for Avast!
Version: 4, 1, 389, 0
Product: avast! Antivirus
Manufacturer: ALWIL Software
sorry I couldn't get a screenshot but I had no way of getting it back here as the computer still can't access the net, and there were no floppy disks around.