Try this little script to sanity check the groups:
 Code:
$=SetOption("Explicit","ON")
Break ON

Dim $sGroup,$iIndex

$iIndex=0

"--Starting enumeration for "+@USERID+@CRLF
$sGroup=EnumGroup($iIndex)
While $sGroup
	IIf(InGroup($sGroup),"  Passed","**FAILED")+" checking InGroup() for '"+$sGroup+"'"+@CRLF
	$iIndex=$iIndex+1 $sGroup=EnumGroup($iIndex)
Loop
"--Enumeration done"+@CRLF