The colours on my monitor have taken on a life of their own. Things will be normal, and then the colours will change resulting in a bilious green/blue hue to all screens and images. I have sent you a print screen of the Windows desktop, so you can see the problem. Changing various Display settings in the Control Panel has not resolved the issue. How can this problem be resolved?

Interestingly enough, the print screen graphic which you sent of the Windows desktop is completely normal - the colours are fine, and there was no hint of anything abnormal. So, this indicates that Windows and the computer are fine, but there is something very wrong with your monitor or video card. This would explain why you would think the problem exists, but the print screen (when viewed on another monitor) displays no abnormalities. My best guess is there is something wrong with the monitor, but we will need to double-check this theory. First, check the monitor VGA cable is firmly connected to the back of the computer (as a loose connection can cause the behaviour you describe). Assuming all is alright, next try to find a different monitor you can use for a few days. In the likely event that the problem does not happen with this different monitor, it looks like the monitor is the problem. I would suggest you junk the old monitor and purchase a new monitor, since repairing a monitor is likely to cost more than buying a new one. You can purchase a new 17′ flat panel LCD monitor for around $275, and 19′ for about $350.

However, should the problem continue with the test monitor, it seems the video card is the culprit in this situation. So, you will likely need to get a new video card. If you are confident working with computers you could replace the video card yourself, but you will need to make sure you purchase a new card which is compatible with your computer (i.e. has the correct connector on the motherboard). If you wish to take this route, I suggest you physically take the old video card with you to a shop and ask for a comparable replacement. If you would like to play it more safe, a computer repair shop should be able to complete the job as well. It is a relatively quick job, so it should not take long at all to complete.