Multiple monitors, Playing games and watching videos

Hey got a little problem.
Just installed Windows 7. and everytime i start up a game (like left 4 dead)
all screens go black(like when they do when you set a other resolution) and back to normal resolution. when game resolution isn't different from the desktop resolution. and cause i ussually have a series running on one of my other monitors i can't see them cause well desktop thinks it not on its desktop resolution(or for what ever other reason it is that video won't show on second monitor if there is a game up on your main monitor that is not on ur normal desktop resolution). this doesn't happen with every game though and can't really figure it out. if u need any info, or have no idea what i'm talking about(don't really know how to explain this very wel) post for more details.
some hardware details:
2x ATI HD3870 in crossfire setup(but not on)
1x 24 inch monitor at 1920x1200
1x20 inch at 1600x1200
1x20 inch at 1400x1050
1x beamer at 1360x768
intel(R) Core(TM)2 Duo CPU E6850 @ 3.00GHz

oe just found that there is a gaming forum to this should probably go there! =)

huh?