How to disable login items per incident, or temporarily
Each time you log in, Mac OS X 10.1.3 or later allows you to choose whether or not your defined login items will open. If you log in normally, login items open. You may choose not to have them open by pressing the Shift key. Follow these steps to disable login items:
1. Start up the computer.
2. If Mac OS X is set to automatically login as a particular user, hold the Shift key during startup as soon as you see the blue background appear with a progress bar and "Mac OS X", then release the Shift key when the login window appears. See Note 1.
3. Login from the Login Window, then immediately hold the Shift key.
4. Release the Shift key after the desktop appears.
Notes:
1. Timing is important. Do not hold the Shift key before the blue screen, the progress bar, and "Mac OS X" appear. For Mac OS X 10.1.3, 10.1.4, or 10.1.5, if the computer is set to automatically login as a particular user, skip step 3 and hold the Shift key until step 4. For more on the automatic login feature, see Mac OS X: Setting up Login, Startup items.
2. Login items are those that you may set up to open automatically, immediately after logging in to the computer. For information on setup, see Mac OS X: Setting up Login, Startup items.