CRM 2011: An unsecured or incorrectly secured fault was received from the other party error when logging into the plugin registration tool

Tried to connect to our online deployment this morning with the plugin registration tool.

However it was unable to connect to the discovery services, this apparently was a known issue on the beta forums and the solution worked for me.

http://social.microsoft.com/Forums/en/crm2011beta/thread/724979a7-769d-4258-acfc-519e36c19e91

Hope this helps

Jonathan