Mac installation error.

I am trying to install Arduino environment 1.0.5 on my Mac but I am getting an error that says "Arduino cannot run because it could not create a folder to store your sketchbook." I have a Mac that runs 10.6.8. I have tried to search the forums but what little information I could find has not helped me solve this problem. I have downloaded the zip folder, copied the application over to my applications folder and run the program but this is when the error show this up. When I unzipped and installed the program it created a file called Arduino in my library and in the Arduino file there is a preference.txt file. This preference.txt file does not contain any information relating to the installation of a sketchbook or a library. What do I need to do to get the program to run on my computer?