We experienced a power failure at our main office which shut down our Exchange server. After it was brought back up all our remote computers at two separate branch locations were unable to connect to the Exchange server using either Outlook Anywhere or OWA. Outlook simply disconnects. OWA generates the error "HTTP 400 Bad Request" after entering the login credentials. Other remote computers outside the branch locations have no problem connecting to the Exchange server using either Outlook Anywhere or OWA. Interestingly computers at the branch locations have no problem connecting to another Exchange server at a completely unrelated business location. Exchange is working fine for all users at the main office. The Exchange server is running Windows 8 and is current on all Windows updates. Servers and desktops have been rebooted. Routers have been restarted. There are no errors in the Exchange server Event Viewer. I am completely baffled as to why only the computers at each of the two branch locations are having problems. Does anyone have any idea as to what might be causing this problem?