In my signature, there is a thread called "Weird Problems". That would be a good place to look for ideas. Other programs like virus checkers or popup blockers can do strange things sometimes.
Make sure there isn't a window behind the player.
Leave it for 30 minutes. You might get an error message eventually.
Is the machine connected to the Internet?
Is MC correctly licensed? Downloaded from our site?
Thanks, Jim. I'll go read the thread.
I just tried it again and this time the window closed, but only after a noticeable delay of perhaps 3-4 seconds. This was not happening on the earlier v13 install I had from maybe a month ago. It certainly doesn't happen with v12 which I use each and every day.
Yes, the machine is connected to the net. Both v12 and v13 were purchased, licensed, and downloaded here, yes.