When certain messages were opened from AM website it throws the above mentioned error.
This is caused by Easybyte tool, which is used to convert messages that were sent or recieved in RTF format and converts them to HTML so that they could be displayed on the web Interface.
You can also notice an error in Vent Viewer on AM server with Source as "Archive Manager Web" Complaining about RTFtoHTML conversion.
Current Resolution involves either re-running in the installer or Upgrading the Client to next version of AM.
