It is most likely that your monitor input cable has twisted or one of the pins in the plug into your computer have become bent. This usually creates a hue shift. I would suggest that you 'wiggle' the cable a little (especially around where the cable comes out from the monitor). Also, take a look at your plug for bent (not missing) pins. If you are an expert and know which pins are supposed to be missing then you can check for that too.

I highly doubt that it is a monitor setting. This does not change when you unplug the monitor.

: I work with Compaq monitors at work and they are not the highest quality monitors. Of course, I should mention that the new ones are much better.

: It is most likely that your monitor input cable has twisted or one of the pins in the plug into your computer have become bent. This usually creates a hue shift. I would suggest that you 'wiggle' the cable a little (especially around where the cable comes out from the monitor). Also, take a look at your plug for bent (not missing) pins. If you are an expert and know which pins are supposed to be missing then you can check for that too.

: I highly doubt that it is a monitor setting. This does not change when you unplug the monitor.

: If your cable is damaged, you might find someone willing to fix it for a inexpensive price, however, it is most likely that you would be better off spending $100 for a new 15 inch monitor or buying a used one for 50 or 80 dollars.