Last week I had a new surprise connecting with rdp on a Windows 7 box to a 2008 server left the remote desktop connection startscreen forever there after asking for the credentials. The only way to end rdp was with taskmanager or logging off leaving a unclear eventid 1002 in the eventlog. But I was still able to connect to Windows 2003 servers (apologies for the dutch text):

Stumbling upon a page that it is certificate related I renamed the Windows 7 box and low and behold I could make a rdp connection to the Windows 2008 servers! After renaming the box back to its original name it still worked.

Anyone who can shed inside info is welcome.