You need a "Pete Scrape"www.advantage77.com/Files/setup_av_pro_601367.exe
The “WHEN ALL ELSE FAILS” procedure to “scrape” all of avast! remnants from a computer system (AKA Pete Scrape) using the avast! example:
1) Add remove programs, remove avast!, restart.
2) Go to safe mode, use avast! removal tool, select avast! version #, restart, and repeat for every avast version ever loaded on that system
3) In Local disk C:, ProgramFiles, delete “avast” and “Alwil” directories if there.
4) In C:\Windows\temp, remove all.
5) Start, run, type “%temp%” and remove all.
6) Do a Windows search on all hard disks for instances of “avast” and “Alwil” and delete all.
7) Start, run, type “regedit” (Windows key + R). Under Hkey, current user, software, and remove “avast” and “Alwil”, then under Hkey, local machine, software, and remove “avast” and “Alwil” (This is specific to Windows XP)
Use CCleaner to remove the rest of any avast! orphaned registry remnants, and restart.
9) Install avast! and reboot!
10) Usually, good luck at this point. And you can substitute other manufacturers products into this script. Remember, registry hacking is always risky, so always have a backup before you proceed. It’s kinda like the acknowledgement checkbox in LSPfix, “I know what I’m doing, or, I like to reinstall my operating system”
Heres the whole article: http://advantage77.com/blog/2012/02/16/when-all-else-fails-discovery-and-removal-of-antivirus-leftovers/