Make sure you have installed the latest versions of DirectX and your video card's drivers. Run the OFP preferences program, OPFLASHPREFERENCES.EXE, and, if your video card supports hardware T&L, make sure you select this in the DISPLAY DEVICE list. Also select a 32-bit resolution size in the RESOLUTION list. If DISPLAY DEVICE was already set to a T&L setting, try switching to Direct3D instead.
If you've got an ATI Radeon graphics card, try enabling the 8-bit stencil option in the direct 3d settings of the card's display properties. Also, consider using the RadeonTweaker utility.
Similarly, if you've got an Nvidia based graphics card, you must select a 32-bit resolution mode, as Nvidia cards don't support the required stencil bufferring in 16-bit mode.
Owners of Kyro chipset based Hercules 3D Prophet graphics adapters had reported this problem when using version 8.162 drivers. Reverting back to version 7.114 drivers resolved the problem. Newer version 9.031 drivers also appear to resolve this problem.
If that still doesn't help, then from the OFP preferences program's main menu, click on ADVANCED. On the advanced options menu, click on the TEXTURES tab and set all list entries there to the maximum values possible. Save the preference changes and try running OFP again.
If this too fails, run the OFP preferences program again and click on AUTODETECT and then on START to see if that resolves the problem.