If your Mac is experiencing problems running, one step for determining the problem is to boot the system into Safe Mode, which is a limited environment that only loads Apple-provided software for basic functionality. Best free painting app for mac. To get into Safe Mode you simply restart your Mac with the Shift key held; however, in some cases this will not work and the computer may simply boot normally or experience a problem and hang without booting at all. The inability to boot into Safe Mode may happen because the system is configured with encryption or other security settings that prevent booting to such modes, because of nuances with how wireless keyboards pass boot arguments to the system, or because of errors in the file system. FileVault in OS X 10.7 'Lion' or later will prevent booting to Safe Mode. Screenshot by Topher Kessler/CNET Security settings Some security settings in OS X may contribute to the inability to boot to Safe Mode. If you have Apple's FileVault disk encryption technology enabled, or if you have a firmware password set on your system, then the computer will not boot to Safe Mode.

To enter Safe Mode, you must first disable these options. FileVault can be disabled in the Security system preferences using the FileVault tab, but the firmware password must be disabled using the Firmware Password utility that is available in the Utilities menu in the OS X installer (You can get to this in OS X Lion and later by holding Command-R at startup). Wireless keyboards A second potential issue that prevents Safe Mode from working is if you have a wireless keyboard. While many instructions suggest that you hold the Shift key at startup to get to Safe Mode, the system's Bluetooth controllers will only activate after the startup chimes sound, so if the key is held before this, the key press will not be recognized. Instead, if you have a wireless keyboard be sure to press and hold the Shift key after the boot chimes sound.

In addition to the timing of the key press, be sure to check your keyboard's battery level and replace the batteries if they are low. File system errors A final issue that may prevent booting to Safe Mode is if there are problems with the boot drive's file system structure. The HFS+ format includes a several indexing databases that hold information on where files are on the disk, and various attributes about them. When you run a file system check with Disk Utility, you will see them listed as the Catalog file, the Extents file, and Extended Attributes file, among others. When the system boots to Safe Mode it will show a gray progress bar that indicates various maintenance tasks are being run at startup. One of these tasks is a filesystem check on file systems structure using the tool 'fsck_hfs,' but if a problem occurs that prevents the tool from checking then it may hang and result in the system only loading to the gray screen with the Apple and a progress bar below it. Unfortunately it is a bit difficult to see if this is the case when the system is only displaying a gray progress bar; however, you can force the system to show you what is going on by having it boot to both Safe and Verbose modes at the same time.

Sometimes, Mac users may encounter a black screen when they wake their Mac from a sleep state. The issue is quite obvious if you experience it; when you attempt to wake a Mac from sleep or open your MacBook lid, the screen stays black, although the computer is obviously awake as often indicated by the keyboard being lit up or even alert sounds triggering from the computer.