Possible problem with xm7-22w xerox.

Hi,
I've had a xm7-22w xerox monitor for a good number of years. No problems with it untill this week when the screen started to fade with some vertical and horizontal coloured lines (usually pink and grey) whenever I boot-up my computer. To get the monitor to work I have to unplug the monitor and plug it back in again and keep pressing the power button on the monitor. Sometimes the blue LED light on the monitor power button would slowly fade and come back on again. All in all takes about 5 minutes to get the monitor working. Once it is working I can switch the monitor off and on with no problems, no fading or anything.
It's just whenever I boot up the computer. I suspect my computer might be having an issue but I thought I'd query the monitor just in case.
Any suggestions?

Edit: the screen went completely white earlier today. I left the computer on standy and when I pressed the keyboard key to wake it up, the monitor awoke but just gave me a white screen and then some lines. Had to replug the monitor and press the power button on and off and the desktop appeared.