Since I installed Lion I was not able to open Preview and therefore I was unable to view PDF files (JPG files etc.). Today I contacted Apple and after rebooting 5 times we found the problem. The error report stated (somewhere in the text): sandbox creation failed: 1002 What we did is the following: We made a new user with admin rights. And opened a PDF under that account, which worked. We then went to Finder->Go pressed Alt and selected Library. In the Library we went to the folder Containers and copied this folder to the shared folder under Users. We logged of the new user account and went into the primary account again. In the primary account we replaced the Containers folder in the Library with the Containers folder we just placed in the shared folder under Users. After rebooting, Preview worked properly again!