If this is happening just after you've upgraded your computer to Windows XP, read here.
Make sure you have installed the latest versions of DirectX and your graphics card's drivers. After installing DirectX or new graphics drivers, I recommend rebooting your PC and running the DirectX DXDiag diagnostic program to make certain everything tests out alright.
One OFP player who had this problem, resolved it by simply running DXDiag, clicking on the DISPLAY tab, disabling the "Direct3D Acceleration" setting and then enabling the setting again and clicking OK to save the settings. After that, OFP ran like a charm. Go figure!
Sometimes, uninstalling DirectX (using DirectX Buster) and/or your graphics drivers, rebooting, reinstalling them and rebooting again can clear things up. Life is full of surprises!
Actually, sometimes installing the latest drivers for your graphics adapter card may actually cause this problem or others. For example, this OFP Network forum thread relates experiences of users receiving the "Cannot create 3D device" message. They resolved the problem by reverting to earlier versions of NVIDIA's detonator drivers. Similarly, this FAQ item discusses a different problem encountered with newer driver versions for a KYRO 2 based graphics adapter card.
Here's another last minute check to perform. Go into Windows CONTROL PANEL and open DISPLAY. Click on the SETTINGS tab and click there on the ADVANCED button. Under ADVANCED, click on the PERFORMANCE tab. Make sure that HARDWARE ACCELERATION is set to FULL and apply any changes made.
After installing or updating any Windows components or device drivers, reboot and run the OFP preferences program, OPFLASHPREFERENCES.EXE. If your video card supports hardware T&L, make sure you select this in the program's DISPLAY DEVICE list.
Also see this item on the BIS troubleshooting FAQ.
If these fail, run the OFP preferences program again and click on AUTODETECT and then on START to see if that resolves the problem.