I am having the same trouble as well folks. Secondary machine with Everquest always runs fine, Primary machine will lock keyboard and mouse input in the game only (you can tab out as others state and kill the game). I have to admit that I also bought Multiplicity just for this game Please see what you can do Devs ... thanks much.
I have a registered version of Multiplicity. I have 3 machines and I use the center one to control the other two. It seems that even the little animation of the mouse moving between the 3 displays on the website works, I am only able to configure it to allow me to slide to *either* the left monitor, or the right. I would expect that you could configure the mouse to slide seamlessly between the 3? I have also configured hotkeys to try to manually choose them, seemingly to no avail