Upgrade to Win 7 breaks dual monitor capabilites on D830 with D/Port PR01X

Hi

I've recently upgraded to Windows 7 from Windows XP.  Under XP I almost always used my D830 laptop with the D/Port PR01X port replicator.  I used the laptop monitor as the secondary screen and an external monitor (connected via the DVI port on the d/port) as the main screen.

After upgrading to Windows 7 I no longer have the option of configuring a dual display.  Windows 7 does not even see the monitor connected to the d/port.  The OS seems to know that it is docked as it gives me the option to 'undock computer' plus the keyboard and mouse (connected via USB) seem to work.  It just doesn't see the second monitor.

I didn't think that the D/Port required any drivers, as all it is is a port replicator. 

I've updated the BIOS to the latest version, tried unplugging cables, docking & undocking the laptop, I tried a hardware search - none of which has lead me to a solution.  Not sure what to try next.

Anyone got any ideas?

Ian