Good day,
I've been fighting this problem for a long time now. I finally gave up last night after loading the v6.1 release software with the most recent 285.62 - WHQL Win 7 x64 Nvidia drivers. When the DisplayLink software is installed, the Nvidia control panel does not function. I'm using a pair of Geforce GTX480's but I don't think the hardware matters in this case as it's all software related.
When I uninstall the DisplayLink software without making any other changes, I get full functionality back in the Nvidia drivers. I ended up connecting my third display to the second GTX480. I had to disable SLI capabilities in order to run that display. Not ideal as now the second card is a rather expensive PhysX board with a third display attached
Any help in resolving this issue would fantastic. I can understand the frustration in trying to get bugs worked out that were introduced by another vendor perhaps, however we're just consumers that want to be able to use these products together.
Thanks!