Thanks guys for all of the replies:
The PSU was changed about 2 months ago as the computer kept switching off.....
The monitor does switch off, but the green light next to the on/off buttonm stays on. It's got it's own power supply directly to the mains, which makes me think it's not the computer PSU. I'll check the video card, but it looks as if I'll have to upgrade
The only answer I wanted I think. Thanks chaps. I really appreciate your time replying.
Regards
Mo