Click on the planeshift folder in the applications folder and then do a get info. If you are the admin on your computer change the permissions to read and write where you can. At the bottom left click n the icon that looks like a gear and choose to apply changes to contents of the folder. After changing your permissions to read and write on the planeshift folder you should be able to run the update form the PS launch application. You might also go to your utilities folder and repair permissions using the disk utility.
