Msg#: 3663436 posted 2:35 pm on Jun 3, 2008 (gmt 0)
Are you on a Mac? If so, in the Finder, in the View menu, (or use command-j) make sure the box next to Show icon preview is checked.
If that does not work, go in to Applications>Utilities and run Disk Utility, choose the First Aid tab and click on the Permissions repair button. Don't wast your time with the Verify disk permissions, just go straight to repair.