I'm surprised how often I see software that just is NOT compatible with the last years version of itself. And then the support people swear up and down on a stack of bibles that it is. Let's see, AutoCAD 2010 is stable as fuck with a 2010 drawing, but try working on an older version drawing in 2010 and you better set your autosave for 30 seconds.
ding!
we still keep 08 and 09 on our detailer machines for just that reason