13w09b Corrupting my current minecraft

I was bored so I decided to play 13w09b for a while... I went to eat and when I came back and attempted to play minecraft 1.4.7... got stuck on the MOJANG screen (After a while it would stop responding). Deleted .minecraft and reinstalled... worked perfectly. Attached is the error file that was on my desktop. There wasn't a crash report in my old .minecraft. I think this is a corruption BUG. this isn't just me, this could affect other people therefore it has a place on the bugtracker.