Remove files from the following locations.
Note: To find the user library folder in 10.7 and 10.8 hold down the option key, click Go in the Finder and choose Library.
For instance if TextEdit keeps crashing delete com.apple.TextEdit folder and then open the app again.
Also in the following folder find the folder of the app that keeps crashing and delete it. ~/Library/Saved Application State/
Launch your application and enjoy!