Mac OS X: The Missing Manual, Second Edition

Program Icons Turn to Folders

You may remember that in Mac OS X, almost every application, behind the scenes, is actually a folder. All you see (and double-click to open) is one icon called Mail, for example, but inside are dozens of folders, icons, and chunks of software code. The only way you’d ever know that a Mac OS X “application icon” is an optical illusion would be to Control-click the application and, from the pop-up menu, choose Show Package Contents.

Every now and then, though—most often after a power failure—Mac OS X puts on a much more showy display of this feature than perhaps you’d like: Suddenly all applications show up as folders, whose names bear the suffix .app. All very educational, of course, but now you have no way to actually run those programs, because the icon to double-click has disappeared.

First Resort: Trash the Three Prefs

Most of the time, the generic-folders problem stems from the corruption of three particular preference files in your Home→Library→Preferences folder: namely, LSApplications, LSClaimedTypes, and LSSchemes. Throw them away, and then log out. When you log back in, your applications should all have been restored to their rightful conditions.

Note

Tossing these preference files also discards any document-to-application relationships you’ve established as described in Section 4.3.4.1.

Second Resort: Check the Disk

Sometimes your NetInfo database—the central database of all accounts, programs, connections, and everything Mac OS X knows about its ...