krank: I see your problem; The user had entered something into the picture field before Avatar Hack was installed and this is why that picture appears. Go into his/her profile in the Control Panel and erase the URL from the "Your Picture" field and all should be fine when the users posts again.
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.