UBB.threads PHP Forum Software Community Forums UBB.classic UBB.classic 6 Support Error message

Spradically getting the following message:

Can't open 'CGIPath/Mish/00000001.cgi'.

Permission was denied - please ask the administrator to check the permissions on that file/directory.

The exact error returned by the operating system is:
Permission denied

Using UBB.classic™ 6.7.1. Any ideas??