LCD TV flashes on/off
 

I have a Sewell HDdeck connecting a Dell Optiflex 960 with Windows 7 to a NEC 46" LCD. I am using DisplayLink driver 7.0.41409.0.

I have a Dell LCD 19" connected via VGA. When I have the units set to Extend the desktop, everything works fine. When I have them set to mirror, the NEC blinks to a black screen for about 3 seconds multiple times per minute. I have the resolution set to 1440x900 on both LCDs.

Any help is appreciated!