Does this happen in any commercial games? (half-life 1 for example...) back when my rig was running on a radeon based card I had lots of problems in full screen games when running dual head (or tripple when I added another card I found in a closet... fyi, don't install cards you find in closets.) but I have never had a problem with an nvidia card and multiple displays, besides the desktop picture size changing but that's just a windows thing.
I can't really offer a solution but I would recommend you test it out to see if it's blitz centric or more your hardware/software config. as it's not that uncommon win windows, especially with ATI cards, to have some strange stuff happen with dual screens.
I can't really offer a solution but I would recommend you test it out to see if it's blitz centric or more your hardware/software config. as it's not that uncommon win windows, especially with ATI cards, to have some strange stuff happen with dual screens.