First, in some cases, the issue is related to a bad time and date setting on your computer.. Check to make sure your computer time and date are correct.. If not, fix them and if necessary, replace your CMOS battery to keep the date correct.
Next, see the link below to make sure the server certificate is up to date and installed on your computer. (It may have changed.) Generally, contacting the server's IT folks will allow you to get this fixed quickly.