We were having the same problem but found a possible solution. When we set up the user account we neglected to enter an e-mail address. Once we gave the account an e-mail address the problem went away. Great! I really had in the e-mail address (at) instead of the real character @. I changed, and ...

Hi all
If I or other isers comment an entry an error will occure: Internal Server Error The server encountered an internal error or misconfiguration and was unable to complete your request.

But I receive the comment and I can moderate it. So the machanism works , but with the confusing error ...