Here is my slightly revised version of your script.

 Code:
break on
Dim $index, $RC, $Group

? "Redirection: " + SetOption("WOW64FileRedirection")
$rc = SetOption("WOW64FileRedirection","OFF")
? "Redirection: " + SetOption("WOW64FileRedirection")

$index=0
$Group=Enumgroup($index)
While len($Group)
  $index=$index+1
  $Group=Enumgroup($index)
loop 

? "Number of Groups:  " + $index

if ingroup(Enumgroup(0))
  ? "In Group 0"
else
  ? "Not in Group 0"
endif


With Redirection Turned off
 Quote:

Redirection: ON
Redirection: OFF
Number of Groups: 14
In Group 0


With Redirection Turned On
 Quote:

Redirection: ON
Redirection: ON
Number of Groups: 14
In Group 0