Windows 7 IE8 Certificate Error

About IE Certificate Errors
If Internet Explorer displays a certificate error message when you try to access a website, the fault is caused by the website or its URL address rather than Internet Explorer. The problem can occur in all versions of Internet Explorer, not just Internet Explorer 8 running on the Windows 7 operating system. The certificate error warning takes the form of a prominent message that opens in the full browser window.
Certificate Error Causes
Certificate errors most usually occur when the user tries to access a site on a secure HTTPS connection. The certificate error displays if the website isn’t configured correctly or if the site server’s certification is invalid or expired. Less frequently, a certificate error can indicate that the website server is misrepresenting its identity, which poses a security risk. However, if the problem affects a site that you trust and have visited without incident previously, the problem is mostly likely due to certificate or configuration problems.
Troubleshooting
Self-help for certification errors is limited because the issue is usually for the website to resolve. One way to get around the problem of bad configuration is to experiment with the URL that you entered into Internet Explorer; for example, if you used “https://example.com” to access the problematic site, try entering “https://www.example.com” instead. If you used “www” in the address originally, try entering the address without this element. If this fails to resolve the issue, the only other option is to contact the website to flag the problem. The website administrator needs to contact his web host or the appropriate certification authority to resolve the problem or renew the certificate.
Visiting Websites With Certificate Errors
Unless you completely trust the website, Microsoft's advice is not to visit sites when Internet Explorer displays a certificate error. Although the warning screen does give you the option to ignore the warning and continue to the site, doing so might put your computer at risk. The reason for the certificate error might be legitimate, but the error can also indicate a security problem with the site or that your Internet connection has been intercepted by a malicious site.