Projectors must re-acquire signals. Why?

Am feeding VGA signals to 2 Dell 4210's and 1 Dell 2200MP with a Dell Studio 17 using an nvidea duel link dvi card (can't remember model right now).  Works great with a signal amp/distributor.  Just added a 4x4 matrix switcher and an older Dell XPS with a ATI Radeon 9600 duel link dvi card.  All signals great at boot up with switcher in any position, but the problem occurs when I switch to the Studio computer as a source.  When switching any computer source to any projector the signal immediately shows the new source for a half a second then must re-acquire the signal.  This usually takes a few seconds when switching to the old XPS but always works.  When switching to the New Studio the signal only re-acquires about 10 percent of the time, the other 90 percent of the time it times out and announces that the signal resolution is incorrect and must be changed to 1024x768, which of course all the computers are already set to.  If I reset the imput source I get the same odds, it acquires the correct source about 10 percent of the time.  The 2200 is the exception.  It seems to always acquire the correct source after a few moments but I'm confused as to why I have a momentary signal loss after switching anyway.  I can see the correct image on each projector after switching for a moment.  Does anyone know of a reason why I would then loose the signal and why the signal from the Studio computer would not be recognized 90 percent of the time?  I'd appreciate any input.  Will be replacing the 2200mp with a new 4210 when I get this worked out, but right now it's the only one halfway doing what I need.  Thanks.

By the way, the switcher is a Conversions Technology 4x4 Matrix Switcher.