Video issues with changing resolution

[Hodsocks]

I am hoping you guys have some suggestions here, I have been looking at a pc which seems to be changing its resolution at random, it will work fine for a while and then the screen will go black for a few seconds and then come back with a changed resolution, it will then go black again and then revert back to the original resolution.
Its a Gigabyte AM3 mobo with AMD onboard graphics.
Thinking it might be a graphics issue I installed a Geforce 8400 GS PCI card which worked fine for a few weeks but now we have the graphics issues again. I am assuming that as it had the problen with 2 different graphics chips, one onboard and one on the PCI card that its unlikely to be a graphics issue.
Could it be an issue with the monitor which is a 17" Dell TFT?

 

[mailpup]

What have you done regarding graphics drivers? Have you tried to install the latest that is appropriate for each card?

 

[Hodsocks]

Hi, yes I have updated drivers to the latest but it made little difference to the issue.

 

[Hodsocks]

Sorry to raise this problem again.
I changed the monitor which seemed to resolve the issue for about 8 months, however recently the problem has resurfaced again. Last week I updated the video drivers which helped for a few days but again the problem is back.
Anyone any suggestions?

 

[Hodsocks]

I am slowly coming to the conclusion that its a software related issue, possibly windows related (win 7), having tried a different video card and a new monitor without success, tried several drivers including the latest, again without resolution.
Yesterday the screen was going on and off every few seconds, I decided to run some diagnostics using my Micro 200 disc which runs on boot up using its own software and outside of windows, it ran for 30 mins plus without any video issues, hence my thought that it may be software rather than an hardware problem, I shall reload all the software and see if I finally reach a resolution.