We have Exchange 2007 running on Server 2008 x64. No matter what changes I make the Outlook Web Access Client times out in a couple of minutes whether you select Public or Private, for all users in the organization. Whether you are accessing internally or externally. They can be in the middle of typing an email and the client will log them out mid email.
I have used some other suggestions and created DWORD values in the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeOWA\ with PublicClientTimeout and TrustedClientTimeout. Neither of these has fixed the issue.
I also saw a suggestion some where to install some hotfix's that might fix it. These did not either....I believe it was hotfix 3?
Any suggestions are much appreciated!