I have a 15 inch early 2011 Macbook Pro running lion. 2.0 ghz i7, 4gb ram, 500 gb hdd at 5400 rpm. The problem I am experiencing is when I play a song through iTunes, the song will skip. It does this with all my songs so I ruled out that first. I still have 1 gb of ram free when it happens too. I also have ran disk utility and repaired disk permission. I am thinking I am just going to have to reinstall the OS. Any ideas?