Hi, It is not enough to just know you use Windows Vista, you must determine if you are using the 32 or 64 bit version. The best way to proceed would be to clear all check boxes from the 'Properties'-'Compatibility' tab and save it. If you now see the "stack error- this application must close" message when trying to enter a lobby you are again ready to configure.
The Self Help FAQ can be found at http://wgcenter.com/help The error is mentioned as one of the "Answers to the two most commonly asked questions".
Please write to technical support if you continue to have troubles at support@wgcenter.com.