Old Appx app and Aero theme?

Anyone trying to use an old Appx client (4.2) on Windows 7? App comes up but doesn't show your typing in the application boxes for authentication. Tried running it in Windows XP mode all the way down to Windows 95. Also tried running as system admin - doesn't even come up. Only thing that did do something - run in 256 mode and disable themes. But this makes the Windows 7 screen virtually impossible to read and/or function in. We are not going to update the server OS version so we were informed not to run a higher client version than the server.

Thanks in advance!