As the title reads, after recording audio, and pressing the stop button, audacity freezes. This doesn't appear to happen all the time, but when it does I terminate Audacity and then recover project upon reopening.
Here are some general tips you may want to have a look at first. Make sure you have the latest version of Audacity, enough memory, etc.: http://theaudacitytopodcast.com/tap040-10-tips-for-how-to-keep-audacity-from-crashing/
If that doesn't help, look in to the known bugs for the current version of Audacity and see if anyone has found a workaround. This one seems similar to what you are experiencing, but maybe not exactly the same: https://bugs.launchpad.net/ubuntu/+source/audacity/+bug/792549