Cliff, Here is the error I get from IE5.50 when trying to send a private message...
Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator, info@(a_server.com) and inform them of the time the error occurred, and anything you might have done that may have caused the error.
More information about this error may be available in the server error log.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
From what I have seen in the past, this can be caused by something as little as a type-o in the script which is causing a runtime error when executing the command set. It looks like it is possible that the CGI is calling a process and attempting to load a nonexisting page. Hope this helps...
Thanks
Bryan