All end users are prompted to enter their credentials after working on application in random manner and time.
We are using SharePoint office 2007 SP2, installed on windows 2003 64x, installed as farm (SharePoint, Database and separate Domain Controller) , we created our custom application which is deployed on site 80, the application is exposed to end users over internet , AAM has been configured , and are using ForteGate firewall, our clients have their own PCs , running windows XP , IE8.
As part of tracing the above issue the Session time out has change set on IIS for site 80 to from (5 minutes , InProc) to (180 minutes , SQL server ), but didn't work.
Client settings on IE to access our application over internet are:
-Adding site to trusted sites, custom level for authentication "automatic logon with current user and password" , previously was " automatic logon only on Intranet zone".
-Some users have stored their password in Manage User Credentials, while other are not all, their password have never been changed.
Trying to fix this issue, SharePoint office and WSS have been updated to SP2, and all Windows updates have been installed.