Winexit not working

Hello All –
I have an issue with Winexit. I am using to force user logoffs via a policy. We however have a problem where some of the machine are getting a user32.dll initialization failure. I checked the technet articles and changed the heap size. It seems that the first time winexit runs – it works fine. Any subsequent runs results in the failure. If I give the users Admin right on their boxes – it will work. All users are in the Power Users group. Any info would be greatly appreciated. Thanks. Mike.