I was using MAC OS 10.6 in my computer and recently I have upgrade operating system to Mac OS X Lion. After upgrading the application to Mac OS X Lion I am experiencing problem with changing wallpaper. Whenever I right click on desktop and select change wallpaper option and then when I select any other wallpaper and click on ok at that time wallpaper does not get changed. Even when I select any MAC default image time also I get same problem. I have open application and the selected disk utility option from the utility menu and then I have repaired disk permission but after trying that solution also I was having same problem. Now after that I have created new user account in my computer and then I have logged in to that account and then when I tried to change my wallpaper at that time I get same problem. This problem is very irritating for me. What should I do to solve this problem?