Mouse Skipping when 2nd monitor used

I've been using a 2560x1600 Samsung 30" on the video card and a USB-->DVI DisplayLink box for a light duty 17".

All great.

I recently added an HDMI 1080p monitor as a third monitor via MDP-->HDMI adaptor, using one of the 2 additional Mini-Display Ports on the video card.

Works great, but as soon as I plug it in, other problems occur.

The mouse becomes jittery, like it loses tracking and it skips a bit so it becomes hard to do any fine work with the mouse.

Additionally, I have a MOTU audio interface on a PCIe Firewire card. When I plug the HDMI monitor in, that interface starts acting strangely; there are little spikes on the meters intermittently.

As soon as I unplug the third monitor, these problems go away.

This problem has been brought up before in other contexts, but the problem seems to remain:

https://discussions.apple.com/thread/3016188?answerId=15073164022#15073164022

https://discussions.apple.com/thread/1965949?start=0&tstart=0

http://forums.macrumors.com/showthread.php?t=1155708

https://discussions.apple.com/thread/3069002

I was on the phone with 2nd tier Applecare and they of course, blame it on my monitor, or an overdrawn power supply.

No, Apple. This is poor video driver code.

Please fix.