I had the same problem as Volans. I use Win2000 and had deleted the Brainbot items after using Spybot S&D. I found the FAQ entry saying to run C:\WINNT\SYSTEM32\REGSVR32.EXE ACTSKIN4.OCX. After I let that run, and the main application window was able to come right up. I didn’t even have to restart Avast. Apparantly this didn’t work for Volans, but it did for me.

This happened before (the last time I ran Spybot, I’m guessing), and my solution then was to uninstall and reinstall Avast. I had no idea of the tie-in to Spybot until I read this thread. I’ll just set Spybot to ignore those specific registry references in the future.