What hacks installed? Any? If you have some, remove them. If not, file a support ticket with infopop or check your perl path above. Upload the files again from a fresh zip.
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.