Hi @ll, I have in mind that this was a common problem some time ago. After log in with right credentials I receive a page with two frames, both displaying the 404 page not found error. I searched OWA troubleshooting guide, KB, google groups, the message boards and this lists archive and did not found anything mentioning that error (except Q829222 which is not the solution in my case) I have a front-end back-end scenario, other BE servers are working properly. When logging on on the BE server directly it works. I checked the firewall and the authentication. Not working. Any other ideas are welcome... Greets, Christian