Monitor Is A Kind Of Yellow colour

Hey Y’all again, it seems im quite a regular on this website… Anyway I was wandering if anyone could help me. I turned the monitor on this morning and it has a yellow kind of layer on the screen and seems really faded. Any help is appreciated…

AMD Athlon XP 2600+
80GB Excelstor HDD
PNY GeForce 5600 256mb
256MB RAM

Cheers – Simon