I am helping my boss with this issue.
1) We have IT support but they do not support personal computer (i called it compA). Fair enough.
2) Why do we use personal computer to work ? because our organization has banned internet in office LT, for security reason. That's life
3) In the compA, i have installed office 2016 and we have been using without problem since last Aug.
4) suddenly, this morning, when we try to launch outlook 2016, connected to our own corp MS Exchange, this problem occur :
There is a problem with the proxy server's security certificate.
Outlook is unable to connect to the proxy server mail.domain.com (Error Code 80000000).
5) OS is win 7.
6) What i have tried
a) deleted and created a new profile for my boss. cannot work
b) created a new profile for myself, same error, cannot work
c) export trust cert in another personal LT and import into compA, cannot work
d) asked my boss to create a new outlook profile in my own LT. No problem. it works.
e) first repaired Office 2016, then uninstall and reinstall office 2016. same problem cannot work.
somehow, i just do not know what cert is office outlook trying to locate.
If you know how should i go about it, please help me.