One of the most frequent causes of problems with software under OS X is the corruption of the preference file of the application.
This is the reason for the proposal to erase the preference file before restarting a problematic program.
Now there exists a program to verify the preference files in anticipation of problems. Preferential Treatment will scan the preference files used by the system and detect those which are corrupt and propose that you trash them. It is available at the following address and it is free:
http://www.jonn8.com/html/pt.html
Note also that in the case of instability, one can repair the permissions of the system (Disk Utility) and also empty the caches with Onyx, in particular those of the fonts.
[translation by crispin]
