mchain
2
What version(s) of avast! were you running?
aswclear.exe removes all remaining deep-level avast! system drivers left over on uninstall, which is why you must reboot your system after running this tool. Hopefully this was done is Safe Mode only.
See here for any other uninstalled a/v’s used in the past: http://www.avast.com/faq.php?article=AVKB11#artTitle