I am using the latest (v1.3.0.2) of TAdvGroupBox and when I display a form containing this component with the checkbox parameter visible on a Windows 2003 server system it throws an "Element Not Found" exception. This only happens when StyleElements.seClient is FALSE. Unfortunately due a previously reported bug, when I set seCLIENT, the checkboxes do not display properly.
If I intercept the exception it does not draw the control at all, but does appear to enable it's child controls based on the setting of the checkbox (set in code).