Users are getting sporadic "Server not found" errors after idling in the browser. We have a HTTPS web application (Apache/Tomcat) using NSS for authentication on the server. The error occurs when a user opens the application and later lets it sit idle/untouched for 15 minutes. When they try to access the application they can get a "Server not found" error. Users use CAC cards with ActivClient software and our web application uses the certificates for authentication and authorization.
We have been able to recreate the problem but have been unable to diagnose it. In recreating the problem the server is getting a series of "Unable to find the certificate or key necessary for authentication" errors in the NSS log associated with the browser error. These erros don't occur until the user tries to access the idle application. When the application is idle for 15 minutes the PIN is not requested yet the PIN Cache timeout in ActivClient is set at 15 minutes. All our server side timeout parameters are set to hours not minutes. IE 6 is our browser and NSS is using TLS. We have tried modifying "SetEnvIf User-Agent ".MSIE." ssl-unclean-shutdown" with no improvement. I understand that the PIN cache timeout and SSL session don't have a 1:1 relationship but the timing is suspicious. Can't find anything in the windows error logs that indicates a problem (security logs are not accessible to us).
Any suggestions as to how to identify the cause of the problem would be appreciated.