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System Freezes in Mac OS

This document explains reasons and solutions for Mac system freezes.

Mac Operating System Freeze

The most useful thing you can do is to set up a fault log in which you record exactly what was going on when the condition occurred. The format below should prove useful:

  • Version of system software is being used
  • Program being run (include version number)
  • Other Applications open at the time
  • List all Extensions, Control Panels
  • What were you doing EXACTLY when the issue occurred?
  • What was the result (freeze, reboot, crash, error message, etc.)?
  • What you tried to do to get out of it and with what results?
  • Did you have to reboot?
  • Did things work okay after reboot?
If the computer repeatedly stops responding, begin the troubleshooting cycle below, note what you do and with what results.
If it becomes necessary for you to take your computer to your dealer to assist you with the troubleshooting, this information will be helpful for explaining the computer's condition.

What Causes a Program to no Longer Run or unexpectedly Quit?

There are many causes for issues of this nature, leading among them:

System Software

A previous system fault could make your application or system software unusable to some degree. The solution is to reinstall system software and, as a matter of good habit, the application. It is usually wise to err on the side or precaution than not - and good practice to keep your copy of system software nearby so that you can reinstall after any serious issue. An incompatible extension or Control Panel after being run, even if removed, may leave "bits and pieces" of itself behind. Reinstalling system software should correct this problem as well.

System and Application Version Incompatibility

Not all versions of system software and application software are compatible. Most applications will clearly indicate what version of system software is required to permit the program to run correctly. If you are using an older version of system software, you may have issues. If you are running current system software, but using an old version of application software you may run into issues. Occasionally, when system software is updated, some earlier functioning applications may fail to perform reliably. This is a compatibility issue, you have only two alternatives: revert to an older version of system software under which the application ran well; or get in touch with the software vendor and inquire about the availability of a "patch" or upgrade.

Out of Memory condition

Some programs require alot of memory. You may discover you do not have enough memory to open, or run the application with all features working correctly. Some programs will fail to open at all; others will open and run for a while until you try to do a cut and paste, edit, print, sort, operations which require additional memory.
You can close the other applications you have opened or obtain more memory.
In some instances, the "out of memory" condition is not real. This situation may exist when a program requires that you have a certain amount of "contiguous" memory available. While you may show that you have 1MB available, and the program only needs 267K, you may not have 267K of memory all in one chunk. Close the other applications you have opened, then launch the program with which you had issues.
Occasionally a complete system restart will be necessary. In some situations, your application may not have enough memory allocated to it to permit it to run correctly: this includes the finder. Select the application by single-clicking on it. Do a "Get Info" from the Menu Bar (or Command-I). If you do not have as much memory allocated as recommended, increase to the recommended amount. If you have the correct allocation, try doubling it to see whether that helps.

Extension or Control Panel Compatibility Issue

Some add on software, such as extensions, control panels, and DAs might not have been written to permit them to be compatible with some versions of system software. This is a situation that you can usually identify quickly. Usually, faults develop shortly after you install some new add on software or after you install a new version of system software. Your only recourse is to remove the offending add on software and pursue a long-term solution with the software vendor or author.

Desktop Manager "Confusion"

The most telling clue to this issue is when you try to open an application by double-clicking on one of its documents, or in trying to print one of its documents from the desktop and you receive the message "application is busy or missing." If this is the case, either your application is busy (for instance, you are trying to run a single user program on a network when someone else is already running it); it is missing (it is unusable or it has been deleted inadvertently); or the desktop manager cannot locate the application. If this is the case follow these steps:
  1. Check and confirm that the application is on the hard drive.
  2. Launch the application and verify that it is functioning correctly.
  3. Restart your computer while holding down the Option and Command keys.
    • A dialog box will inform you that rebuilding your desktop will take a few minutes. You are no longer required to hold down the two keys.
  4. Click OK.  Your desktop will be rebuilt, and you should be able to continue without any issues. For best performance, rebuild the desktop periodically.
  5. This information was adapted from information taken from the Apple Knowledge Base