The problem actually lies with the windows action centre or rather the WMI. This is something which has been the same for several generations of the windows action centre/windows security centre and it isn’t just restricted to avast, but other security software.

You don’t say what OS you are running.

See http://windowsxp.mvps.org/repairwmi.htm, this also mentions Vista, so that may be valid for win7.
For Windows 7 also see Win7 WMI Repair
Also see http://windowsxp.mvps.org/repairwmi.htm, this also mentions Vista, so that may be valid for win7.
Windows XP SP2, SP3 Start, Run, type cmd and click OK from the command prompt type ‘rundll32 wbemupgd, RepairWMISetup’ without the quotes and enter.
Win7 - Also see windows Fix It - http://support.microsoft.com/mats/windows_security_diagnostic/