ChoosePixelFormat/DescribePixelFormat crash with 2 NVS 510 and 5 monitors

I have a user of my OpenGL application which crashes on their system as soon as either ChoosePixelFormat for DescribePixelFormat is called. I’m at a loss on how to approach this (basic troubleshooting done, recent driver, etc).

They have two NVS 510 cards (not SLI) and 5 monitors (4 on one card, and one on the other). According to dxdiag, four of the monitors are 1440x900. Two are connected via “Displayport External” and two through DVI. On the other card is a 1920x1200 monitor connected via “Displayport External”.

Is there anything special that needs to be done with their system? A different driver or something?

Any help is much appreciated, thanks!