I've looked through a ton of pages about this and haven't found any information on the problem i'm experiencing. For information I'm using ubuntu 12.04 32bit desktop edition, fresh install.
I downloaded the .jar file and executed it with no problems. The problem is the that the game will not download and update the required files to play the game. after logging in and hitting "Play Demo" it goes to a screen which shows the progress bar 80% complete and says "complete" and then just stops. After going back to my home folder and looking at the .minecraft folder; there is just and empty /bin folder and no files.
I tried downloading the .exe file and running the game under wine, and I got the exact same problem. I tired turning off the ufw, no change. And for a comparison i tried installing starcraft 2 which worked, but it could not find the patch server, so I think it is some kind of network problem? Any help would really be appreciated this is starting to drive me crazy.