Inspiron 9400 IRQL error

Every so often, the system crashes and displays a full blue screen with white text describing an error message. It says IRQL_not_less_equal_to or something of that sort, then suggests restarting the comp in safemode and removing the device driver. I suspect it is the video driver, so i tried a new one, but it was not Windows Logo tested, and - if anything, has increased the incedence of this error.
Has anyone else had this problem? I haven't narrowed it down to doing any specific action on the comp, but it has happened playing a 3D game (Oblivion booyah!) and once during comp shutdown, and while surfing with mozilla firefox.

Soooo, if it's a graphics driver update i need, where could I find a solid one for a NVidia GeForce Go 7900 GS? (I already have the latest one from the NVidia site)

Thanks