I’m having trouble with my desktop and laptop. Whenever I restart action center notifies me that avast is turned off. What is the problem? They are both running Win7 Ultimate - one 32 and the other 64.
Sometimes, Windows Security Center stops recognizing your antivirus or firewall… So, check your system time and date and also http://forum.avast.com/index.php?topic=23457.msg193534#msg193534
See also: http://windowsxp.mvps.org/repairwmi.htm
Also, can you try to repair your installation?
Go to Control Panel > Add/Remove programs > avast! antivirus > Remove. Then choose Repair function in the popup window (Repair).
Did you have any other antivirus before avast?
Any other security program installed?