I have the same problem (the "looking for software updates" box just disappears after a couple seconds), and none of the "tricks" have helped me. I've tried multiple times over the course of the last two days. What sucks is, I saw a few people that live in the same city as me say they successfully got the update, in various topics about it, so I can't imagine it's a location thing...
What sucks even more is, when the MR1 update came out, I was able to get it just an hour or two after people around here were posting that it came out. Not only that, but prior to the update coming out on Friday, I had been pressing the "check new" button almost daily (as I wasn't keeping up on the news about the update very much, so I was just checking to see if anything came out), and it'd always just say that no new updates were found. Then Friday rolls around, and it doesn't do that, it doesn't give me a "Server unavailable" message, it just does nothing. :/