You have my full sympathy regarding Audacity.  I have come to
suspect that it is partially written by Microsoft people.  (^&
It crashes very frequently, compared to the applications that
I'm accustomed to.  (Do you get core files?  If so, I'm curious
where it crashes for you.  When I examine a core file in gdb,
I have found (in 4 or 5 cases) that Audacity crashed in the
libm floor() function.)


My first thought (which you've probably already checked) is that
your case sounds like Audacity has left a process running that is
holding the audio device open.  (Not only is that my first thought,
but so far it is my only thought.  (^&)

-- 
  "I probably don't know what I'm talking about."  http://www.olib.org/~rkr/