This is actualy a bug in Safari. When you connect to a SSL protected site (HTTPS) the site can also authenticate you with a certificate file. This is not widley used and you don't need it if you don't know about it.
The problem is: the server is telling Safari that it *can* accept a client certificate and safari is trying to send (a wrong) one.
I ran into this while adding SSL Client Authentication to our corporate website (to identify our employees, not customers).
To make matters worse if you only have one com.apple.idms.appleid.prd.xxxx certificate then Safari will silently send THAT certificate which will fail the authentication check, effectivly locking you out of the server.
In my testing it appears that chrome and firefox do handle this situation as appropriate (they do not send a client certificate if they don't have one matching what the server says it will accept).