There appears to be a growing trend for Anti-virus manufacturers to abandon support for older versions of operating systems, and Vista appears to be the one catching the brunt of it.
In April this year we started getting a rash of reports that the new version of Avast! was giving problems. that seemed to die down in about June/July
In the past couple couple of weeks, we have been seeing reports that Symantec Endpoint, and BitDefender are causing similar problems.
In all cases - an error in the licensing section - C:\Windows\system32\slmgr.vbs(291, 5) (null): 0xC004D401 - note that the numerics may change
Avast - Typically, the problem will often show as both a Kernel Tamper, and a Mod-Auth Tamper –
TTS Error: K:20110618155223762-M:20110618122132007- where the numbers are a numeric timestamp at around the time that the new version of Avast was installed – note that in some cases, only one of these errors may show
Symantec Endpoint and BitDefender – these show a Mod-Auth Tamper
- TTS Error: M:20111111153351704- - again, at about the time that the AV was installed
Vista – only RTM and SP1 appear to be affected - builds 6000 and 6001
Uninstall the AV.
Use Windows Updates to install all updates, and get to SP2 level, or install SP1 and SP2 from the standalone installers.
Reinstall the AV.
Check the solution works. Run another MGADiag report, and post the result in YOUR OWN thread – not someone else’s. If you don’t already have a thread of your own, start one, and tell us some background.