Pech

I don't see where or how you can read this as a valid check in KiXtart.

IF "%OS%" == "Windows_NT"

That is batch language, not KiXtart.

You can do an IF @INWIN=1 or IF @INWIN=2 to check if it is NT or 9X

Don't forget that with the SELECT statements the first one that is TRUE will be the only one completed. If the user is in 2 or more groups and you want to check each you will need to use the IF ELSE ENDIF method.

Also you can use the /F switch on the batch file that calls the RunScript KIX32.EXE RunScript.kix /F