I have a trouble with last version avast Home. In profile with administrators rights it works normally, but when i login to profile with user rigths, windows starts with an error and in systemtray there is no icon of Avast. Error in screenshot.
Try this, please:
http://forum.avast.com/index.php?topic=21448.msg182517#msg182517
Find by myself. Add permition to problem user to files WINNT\System32\msvcr71.dll and WINNT\System32\msvcp71.dll