Run as Administrator turned on, but greyed out - can't remove

Run this program as an administrator
is greyed out and can't be changed

On a Windows 7 Pro PC, in the program compatibility properties for a document management program we use (ie. right-click > Properties > Compatibility) there was a ticked 'Run as Administrator' option causing problems with the program failing to load. Issue was it was greyed out so couldn't be removed, even after clicking Change for All Users and entering the administrator password.

Answer was to start up Regedit and track this key down:
HKEY_CURRENT_USER

    Software

        Microsoft

            Windows NT

                CurrentVersion

                    AppCompatFlags

                        Layers

There was an entry for the exe, specifying RUNASADMIN WINXPSP3 - so we just deleted the RUNASADMIN term and all was fine again :-)