U2412M monitor - won't allow proper display resolution

Hi.

I just bought a U2412M 1920 x 1200 monitor.

My system is a Windows 7 64-bit with an Nvidia GTX 260 video card running the latest Nvidia drivers.

When I first attached the monitor it was only showing a Generic PnP monitor in the device manager.

So I installed the driver that came with the monitor, and it then showed a Dell U2412M(Digital) monitor in the device manager.

The problem is when I go to change the resolution it says that the display is a Philips 170B2 (?) monitor and it won't let me set a resolution above 1280 x 1024.  This is the same monitor it thought it had before I installed the driver.  It's like the driver didn't change anything.

When I display the driver file details it shows the following 2 files:

C:\Windows\system32\DRIVERS\monitor.sys

C:\WINDOWS\system32\spool\drivers\color\U2412M.icm

The GTX 260 has a maximum display resolution of 2560x1600, so that shouldn't be the issue.

Please help or I'll have to return the monitor.

Thanks.