Do you mean you are getting error pages that say Untrusted Connection (or similar)? Usually there is an error code on the page, either immediately visible or inside a Technical Details section you can open. It is in parentheses and (separated_by_underscore_characters). Can you paste the code or codes you're getting into a reply? Also, when changing the system clock, please double-check the date, time zone, and daylight savings/summer time settings. Certificate validity checks are indeed sensitive to time discrepancies.