The requested item could not be loaded by the proxy.<P>
The certificate issuer for this server is not recognized by
Netscape. The security certificate may or may not be valid.
Netscape refuses to connect to this server.<P>
[download]

It seems that the proxy doesn't allow you to connect to SSL sites that don't have valid certificates (from its point of view).

Modify the proxy configuration to clear this restriction or, if you have a custom certificate issuer, you can install it in the proxy (it's you choice).