Lion is aggravating me at the moment. First my Mac will sleep in the following circumstances: When the lid is closed When the Macbook is rebooted without opening any applications. However, once I start opening applications it is literally a coin-flip on which application will cause it to skip the idle sleeping process. Most recently it is Mail. When Mail is open my computer will not idle to sleep. (I have exchange set up and that's the only possible thing I could think of that would cause this.) Sometimes it will happen due to Safari, but I think it is a webpage by webpage problem. But there are some webpages that are just normal webpages that will keep my computer from going to sleep. Everytime before a test I run "pmset -g assertions" in terminal and it always says that everything is a zero except 'EnableIdleSleep = 1' and there are no Kernal assertions. If anyone has fixed this or has some advice I would be very interested.