What is the exact certificate error message that you get when you try to access websites?
Step 1: Follow these steps to fix the certificate error:
1. Open Internet Explorer and verify that the page you are trying to view is listing a certificate error.
2. To clear the certificate error, go to Tools --> Internet Options from the menu.
3. Click on the Advanced tab and scroll down to the security section. Clear the boxes for: "Check for publisher's certificate revocation" and "Check for
server certificate revocation".
4. Click Apply and Ok.
5. Attempt to reload the page by clicking the Refresh button at the end of the address bar or by pressing the F5 key. Your page should now load as expected.
Step 2: If that doesn’t help, then refer this KB article and follow the steps:
Warning message when a user tries to connect to a secure Web site by using Internet Explorer 7 or 8: "There is a problem with this website's
security certificate" http://support.microsoft.com/kb/931850
Step 3: If the issue persists, then optimize Internet Explorer.