is that the correct path to your ubbcgi directory ? If not you'll need to modify your config, if it is, then is the file ubb_lib.cgi actually there, and readable ?
Donate to UBBDev today to help aid in Operational, Server and Script Maintenance, and Development costs.
Please also see our parent organization VNC Web Services if you're in the need of a new UBB.threads Install or Upgrade, Site/Server Migrations, or Security and Coding Services.