PL/SQL Developer preferences on Vista
AllRoundAutomations PL/SQL Developer has a bug under Windows Vista which forces the program to reset all user preferences to default values on restart. To solve the problem run it as Administrator.
There is an alternative way to overcome the issue - just set a deny write ACL for
C:\Users\%USERNAME%\AppData\Roaming\PLSQL Developer\Preferences\%USERNAME%\default.ini as all preferences has been configured and before the program starts once again.