The recently released OFP version 1.96 beta upgrade patch includes definite resolutions to this issue. Make sure you carefully follow the patch's installation instructions. When running OFP, verify that you're not inadvertently running an earlier version by checking the OFP version number displayed at the top-center of OFP's main menu.
Should the problem persist, you may need to resolve this problem by reducing the number of unofficial addons from OFP's ADDONS subdirectory or completely removing them altogether and placing them elsewhere. OFP internally maps information about all present addons into memory and this can trigger storage shortage errors. A great way to manage your addons, by the way, is with mod folders.j
If you've done all of the above and still have this problem, try using the newly introduced -nomap parameter on OFP's command or target execution statement in a Window's desktop shortcut. The -nomap command line switch causes OFP to use a different file access technique when a memory mapping failure occurs. There is a slight performance expense if the -nomap file access technique is triggered but this should get you up and running.
OFP Player Evil-One said the above only worked for him after he removed the -nosplash switch from his shortcut's command line. Go figure but it's worth a try, isn't it?
Still having problems or you can't install OFP 1.96 beta for some reason? Read on ..........
Several OFP players began reporting this error in February 2002. The message is most often issued in regard to a large PBO file (e.g., 1985.pbo, music.pbo, o.pbo and others).
This error may occur even when you seem to have ample RAM and free disk space. If you've got an ATI Radeon card, try installing newer drivers. Also try reducing your PC's AGP aperture size in your system's BIOS settings.
Another possibility is that your system is short on memory. If so, solutions range from buying more RAM to using a memory manager program, terminating other executing programs, rebooting or a combination of these. Also check your Windows virtual swap file settings, as a larger swap file has been known to resolve other memory shortage problems.
Supposedly this problem should have occured less often in OFP: Resistance, as OFP's internal management of addons has been improved to reduce memory usage. However, if you experience this problem with OFP: Resistance, the procedures above are just as relevant. In addition, have a look at this Tweak3D article on the subject of AGP aperture size settings. After decreasing his AGP aperture size to 32MB, OFP player Forrest Thiessen no longer received OFP's "CAN'T MEMORY MAP" messages and was finally able to play OFP: Resistance. Your mileage may vary.
Got an ATI Radeon video adapter? Read here as well.
If you've got OFP: Resistance and none of the above solved the problem, here's a wild solution that was suggested to OFP player Ginbo by Codemasters support. Their suggestion was to edit Resistance file O.PBO in the \RES\ADDONS folder, delete the new 46 byte prefix data at the beginning of the file, save the changes made and try running OFP: Resistance again. Amazingly it worked and Ginbo is now a happy puppy! If you resort to this solution, why not do it the easy way, by downloading OFP player Lobanak's itty-bitty utility, CutPBO, and let it automatically do the dirty work for you?!