Sounds like a compatability issue then with your screen and your machine then. This does happen as my bro bought a TFT for his PC, and it simply would not work on his PC. Just showed a scrambled image all the time. Plugged it into my machine and it was fine! Also on my family machine, worked a treat. My TFT worked spot on with his machine so it was simply a compatability issue....

Tried a different monitor with your machine?