CTR monitor? Over 4 or 5 years old?
This is a sign on an aging CTR monitor. Over time, all CTR monitors will show that problem to some extent, and it tends to grow bigger over time.
First thing you can do is to reduce the brightness setting, possibly goint all the way to the minimum. Set the contrast setting to the maximum.
This will aleviate the problem and give you a workable environment.
If the problem keeps geting worst, it's that your monitor is dying. You need to change it.
Electro
July 2011