My monitor screen has been flickering badly of recent (I can get a really good strobe effect by waving my fingers in front of it)

It was having problems when my C drive was too full, but that's been fixed now and the flicker (which improved a lot when we cleared up the C drive) is now back again.

Any ideas as to what might be causing the problem? It's at a level where it's starting to make my eyes uncomfortable.

Now solved - thanks, davidcook .