8400GS + Dual Displays + Vista x64

I have a brand new HP DC7800 business class Desktop with a Nvidia 8400GS. This particular card has a DMS-59 port and in my set up is using a DMS-59 to dual DVI dongle powering dual Viewsonic VP2030B LCDs. When i first got the computer everything was working perfectly, Screen two was set up to extend my desktop from screen one.

Then one day everything stopped working. The computer recognizes that I have both displays hooked up however I can only get video on one of them. In the Nvidia control panel when i click on "Configured independently from each other" and then click apply, my settings get reverted back to single display automatically and I never get picture on the second screen. Same thing happens when i change the settings in windows. I'm running Vista x64 enterprise edition. I have tried swapping cables, different drivers including beta. Any suggestions on what to do next?

Thanks in advance for any help offered.