I think I've figured out what was causing the trouble.
One of the tabs on my Firefox was causing it. Every time it refreshed itself, the disturbances occured. Tried closing it down and so far so good.
I've had a small suspesion it was causing it for alittle while.
I know Firefox has added a function that lets it use the grafics card to power grafical content on webpages, but that was awhile ago.
Still, I will try and do as you said this weekend, and see if it helps.
It still shouldn't be this way. I've had that particular page up for a looooong time and it never caused any problems before.
Thanks in advance. I will let you know how things go as soon as I've done what you suggested and given it a fair amount of testing time.