Welcome to the forums. Although I’ve never had a dual monitor setup, I have seen this error before I upgraded my hardware. It pops up from time to time on the forums, so there a couple threads I can link you that might have solutions you can try.
If none of those work, you could try using the search function (I used the search term D3D to find these results) for more threads that might point you to a possible solution. If it ends up being a particularly difficult problem, one of the Funcom team might ask you for log files or something. Good luck!