Try this 1
1) Right-click on "Internet Explorer" icon --> Properties.
"Internet Properties" window will be opened. Click on "Advanced" tab.
Scroll down to the "Security" section. Under security section, uncheck the
check boxes for "Check for publisher's certificate revocation" and "Check for
server certificate revocation", now look for the options "Warn about certificate
address mismatch & Warn if changing between secure and not secure mode"
and uncheck those options also --> Click on "Apply" button.
Now try to open that website. If the problem still exists then follow the next step
2) If you find the option regarding installation of certificates then install the
certificates related to that site.
3) Add that website to "Trusted Sites".
Right-click on the "Internet Explorer" icon --> Properties ---> Click on "Security"
tab--->Select "Trusted Sites" --> Click on "Sites" button --> Add your website url
in the text box (Example: http://www.example.com)
and click on "Add" button -->
Uncheck the option "Require server verification (https:) for all sites zones in this
zone" and click on OK.
4) For more information regarding certificate errors, click on the below link