I\'ve just updated to BOINC and the BOINC client can\'t connect to the server.
Error message : \"There was an error connecting to the registration server. The server may be down or your proxy settings may need adjusting\".
I\'ve disabled Windows XP firewall and my own firewall (McAfee) too, nothing works.
What can I do ?

This is an error from the old client .You can remove/un-install it
( control panel under Add/Remove Programs climateprediction )

You should also choose to run only one firewall, I've heared that there can be problems if you run more than one.