So far, everyone that has experienced this problem determined that it was caused by an unofficial modification to OFP, especially by Satchel's Dynamic Range sound pack.
To resolve the problem, remove the modifications made, restore OFP's original files (you did make a backup of course, didn't you?) and see if the problem is resolved.
If the problem continues you mat need to reinstall OFP. Follow this thorough reinstallation procedure to play it as safe as possible.
If the problem is resolved, try installing the unofficial modification again and see if you get the error message.