Next time this happens go into Windows Event Viewer and check the logs for error messages.
I work at home and vpn into the office. Once there I open apps that I use for the job.However there is one app that will not let me past the login. I have seen a message about an expired certificate, but the main message is unauthorized error 401.
I have been told that it is a firewall issue. I have McAffee and looked at the firewall settings and do not see anything about certificates nor do I see a blacklist for that app.
Any help will be appreciated