A support ticket has been already submitted Ticket Number 2B5-165B9C11-68DB but maybe someone else has been through this before. HGS worked fine when installed and after SP1 but since recently it would not display any information. Control box on center pedestal works fine, CLR button is not activated, brightness control checked, DLL.XML checked as per PMDG KB, uninstalled and reinstalled again, FSX.CFG checked... I cant think of anything else.. Anyone?

The only thing I've ever seen cause the HGS display to not appear (aside from the cockpit settings you described) is the dll.xml file.