I was in the process of designing a beautiful chart on my new Mac when I got too confident and decided to modify the toolbars of PowerPoint 2011 and... lost all my work again (see my previous rant about this bug)
In sbort: if you customize your toolbar in PowerPoint 2011 for Mac, the program will crash as soon as you enter slideshow mode. Googling around reveals that many users have similar problems: corrupt toolbar files that cause crashing. I decided to dig a bit deeper and through a process of trial and error found that the offending customization button are the straight arrow ones that you find in the autoshape menu. The icon of these bars still have the old PowerPoint 2008 look, I think Microsoft forgot to update them.
They are probably not that many geeky PowerPoint users that would customize their toolbar with straight arrow connector buttons so it would have been hard to uncover the bug. :-)
I am forwarding this post to someone in Microsoft I know, but if there are any Microsoft MVPs reading this post, please pass it on and ask Microsoft to fix the bug.
The post that I originally planned to post will to have to wait a bit...