My monitor flickers every time i reboot, every 15 seconds or so I get a glimpse of the screen.

After trying some recommended fix by supplier (clearing CMOS battery), it still didn't work.

I connected someone else monitor and that seemed OK.

Now I can eventually get my monitor working by removing video cable before booting and then reconnecting it 4 or 5 times!!! (very strange)

However, if I close PC down same thing happens, I can't even just switch monitor off

Any ideas what is causing this???

THANKS