Vista Media Center Black Screen

I have Vista Ultimate 32 bit hooked to my LCD TV using VGA and get 1080P. It has been working for over 2 years. Now when I execute Media Center I get on my TV screen black screen with TV generated message of "Not Supported". My guess is Media center must be coming up in some other resolution. I searched this forum and most proplems with VMC not working are due to compatibility with TV tuners.
Any help would be appreciated.

Thank you