Windows Small Business Server 2008, SP2, All updates installed. Domain Controller. Exchange Server 2007 version 08.02.0254.000. 4 user workstations. Windows 7 (All updates installed). Office basic suite (Outlook 2007 (12.0.6535.5005) SP2 MSO (12.0.6535.5002)). All joined to the domain. Each workstation has 6 user profiles (to allow hotdesking) the profiles are stored locally. After running outlook at what seems random times a windows user login box appears with the username prefilled prompting for a password, you enter it but the box reappears (at this stage Outlook disconnects from exchange), the box does to go away. The user has to exit and restart outlook and all is fine until again at what appears to be random time the box will appear again. When you Test E-mail Autoconfiguration (control right click on outlook icon in system tray) the results look fine. I tried to install KB 957909 but receive a error "The expected version of the product was not found on the system." Thanks in advance for help.

Check in event viewer when a client gets disconnected or else initiate disgnostics logging on the exchange server . ( apperas that the network connection is breaking)

What is the status in OWA ? chimney (tcp offload) is disabled on client and server and also disable TCP/IP V6 in one client and veirfy.Anil