Compatibility of avast with:
a) Kaspersky: is an antivirus, follows the general rules: two residents will conflict.
b) PC-cillin: is an antivirus, follows the general rules: two residents will conflict.
c) Ad-aware: no trouble. It’s not an antivirus. The resident (ad-watch) won’t conflict.
d) SPybot S&D: no trouble. It’s not an antivirus. The resident (tea timer) won’t conflict.
e) Panda: does not encrypt their signature files. Will be detected as false alarms by other antivirus. (as someone mentioned there is no perfect AV out there).