monitor turns dimmer, greenish or yellowish colour

i can't fix this problem. my monitor suddenly changes into dim colour, somewhat green or yellow. please help.

strange :\
try checking the cable is in properly. might of come loose?

or maybe your graphics card could be dying.
I doubt that though how long have you had it?Ephexis

funny. when my monitor changes into a dim colour i just tap it once or twice and it goes back to its normal colour. the problem seems to be inside the monitor. i have had my monitor for about 5 years, my graphic card, ati 9600xt, for 3 years.

thanks for your reply.