Monitor displaying yellow tint

One day, without any warning, I booted up to find a yellow tint on everything – starting with the boot up command prompt and continuing into windows. I did some troubleshooting…I tried my monitor with a different computer – looks fine. I tried my computer with a different graphics card – looks fine. So, the obvious assumption is that my card went bad and I should get a replacement. Right? WRONG. I bought ATI Diamond Viper 9600XT AGP card as a replacement and the same problem persists. I am running a Dell Dimension 4300 Pentium 4 1.5ghz. No visible hardware conflicts, etc. Any ideas? The fantastic tech support staff at Diamond havent responded to my emails.Im banging my head against the wall.