Beginning with Mac OS X Lion when you restart the system it remembers the state of applications on shutdown and attempts to resume them on restart. This tweak allows you to disable this functionality.
Start a new Terminal session (in Finder click Applications > Utilities > Terminal).
To disable this setting, type (or copy and paste) the following command:
defaults write NSGlobalDomain NSQuitAlwaysKeepsWindows -boolean false
To reset this setting to the default value, type (or copy and paste) the following command:
defaults write NSGlobalDomain NSQuitAlwaysKeepsWindows -boolean true
Close the Terminal session by typing
exit at the prompt.
Disclaimer: Making any changes to your system can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from these modifications can be resolved. Please follow the instructions carefully and use the information provided at your own risk.