blurry image on second monitor with data transfer switch

Hello All and happy new year.
I am currently building a generic twin cockpit and have a quad core pc with an Nvidia gt450 card and a second pentium 4 pc with an on board graphics card.
I have the main picture on a projector and the second output from the quad core going to a seperate screen for the instrument panel ( undocked and dragged to it). I use the pentium pc to run a sat nav program view peter dawsons wide fs. I have added a data transfer switch between output two from the quad core and the output of the pentium machine so that I can switch between dual instrument panels and on instrument panel on the left and a sat nav on the right.

When I have the switch set to give dual instrument panels ie one left one right the picture is fine but as soon as I switch to get instruments on the left and sat nav on the right the left hand monitors image looks like it shifts very slightly to the right giving a blurred image.

Does anyone have any idea of how this can be resolved or is it something quite common when using switches? Any help would be greatly appreciated.

regards

HH

Main machine - vista home premium 64 bit Intel Core 2 Quad Q9400 2.66ghz
(RAM): 4,000 MB Hard Drive Capacity: 1,000 GB
Nvidia 9800GT 1024mb DDR3 Graphics Card - Second machine hp pentim 4 3.0 ghz processor