I think the biggest cause of this problem is the number of legitimate companies that don't keep their certificates up to date. I've received those warnings befo

I think the biggest cause of this problem is the number of legitimate companies that don't keep their certificates up to date. I've received those warnings before from Microsoft, Sun, etc... and checked everything else I could to ensure that it was a legitimate communication before proceeding. In the end, the transaction was legitimate and no harm was done - they simply had an expired certificate. As a result, I lost practically all trust in the certificates.