Look at the picture in OP.
The control window is blue. That means the monitor itself is fine. So, it would have to be the computer or the cable like Darkness said.
Lol at Citrus talking about the "color guns" and telling you to degauss it. I don't think i've even seen a CRT monitor in a few years.
If your monitor looks anything like this, you have another problem.
A possible solution:Go to "Calibrate display color." Just type that into the start menu if it's 7. You can make the colors all green (or reverse it) from in there.
Oh, that isn't 7. I don't remember what OS that is but it's filling me with nostalgia. You should be able to find something similar.
Thanks, I also thought it was the problem considering the other monitor worked fine with it. (used a different VGA)
A better way to experiment:
1. Try another monitor with the same cable.
2. Try the same monitor with a different cable.
3. Try a different monitor with a different cable.