Here's an interesting mystery for you: I wrote an article with this title back in 2005, with the original question thusly:

"Dave, I was hoping you could help on this really security alert that keeps on coming up every time I go on the Internet. The alert states the following:

Information you exchange with this site cannot be viewed or changed by others. However, there is a problem with the site's security certificate. The security certificate was issued by a company you have chosen not to trust. View the certificate to determine whether you want to trust the certifying authority. The certificate is valid and the security certificate has a valid name matching the name of the page you are trying to view.

I would be very grateful if you could help stop this security alert from appearing in future."

Dear Dave, I was reading your article Security certificate expired problems? Maybe it's your PC's date and time. and I think that might be my problem. But here's my question: Could you please tell me how to find the date and time and change it?

I'm trying to get Microsoft Entourage on my Mac to work with an SSL-based mail server, but every time I try to use it, I get errors about "unverified root certificate" or uninstalled root certificates. I've dug around on my SSL server and can't figure out what the heck Entourage wants. Help!