nabster83 and harley22, I had the same issue (even with my own server). The problem arises when the remote webpage requires a client certificate – which is rare. Additionally, this makes only sense, if the webpage requires the client certificate optionally, which is even rarer. Finally, you need to have only a single client certificate in your Apple Keychain (for example the Apple ID one). Then Apple Keychain asks you whether to sign.
My solution:
- opened Apple Keychain
- searched for idms, one object of the type certificate appeared
- export that certificate (back it up for the furture)
- deleted that certificate
Because that Apple certificate is going to come back when you use iChat for example, this is not a long-term solution. Therefore, I filled a bug report (radar://14426316). Until this is resolved, the only solution I see, is to use another Internet browser.