This seems to be caused by locked permissions in a home directory file.
1) Make sure BeerSmith is not running.
2) Find your Home directory and delete the file "BeerSmith2-USERNAME" if it exists where USERNAME is your user name.
3) Reboot your machine.
This lock file is the most common cause of the problem.
If it persists, the next step is to make sure that your account has permission to write to /Users/[USERNAME]/Documents/BeerSmith2