Just wanted to let you know, after a reboot (W7Pro/64) SA started up quickly asked me to update to the latest version and I have had no issues since then.
Though I am not sure if this was a coincidence o there was indeed something wrong. The SA version having the issue was the first production release of 2.1 (Build 284 I think). Now I am on Build 288 with no issues.
In the beginning my computer used intranet-only IP and therefore IE had proxy set. Later my computer changed to use IP which can access internet but I forget to remove the IE proxy settings. Safari and Chrome could access Internet without Proxy settings.
Just dunno why and how this forgot-to-remove IE proxy settings affected SA registration.