[mikester]

Are you sure their CERTs are actually good? It could be a number of things causing the error.

The cert itself could be expired, the intermediate certificate on the server (for the certificate authority - like verisign) could be expired or the dns name of the site could be different from the actual name on the certificate.

If the certificate is not configured properly and it's a production system, well, makes me wonder what else is overlooked...

Usually the error message tells you what is wrong with it - what's the error message?