It's a morrowind folder: No, Morrowind files are missing.
Latest game version (1.6.1820): The exe file is missing.
Tribunal and Bloodmoon are installed: No, both the expansions are missing.
UAC is dissabled: Yes.
I don't know about the first one but I do know that I have the right version and I certainly know that I have both expansions installed (Steam GOTY edition).
I will keep posting problems as they occur (well there's another one but it seems to be nothing ATM.)
~Manly Man