Mac OS X 10.5: What you can do if Safari quits unexpectedly

Resolution

Update your Apple software

Make sure that your Apple software is up to date. Software that is out-of-date may lead to incompatibilities with some website content.
 

Update third-party plug-ins

You should make sure any third-party plug-ins are up to date. Some third-party plug-ins may put an icon in System Preferences--if so, see if its preference pane includes a "Check for Updates" feature, then use that to find available updates. You can also check with the vendors of third-party plug-ins to see if any updates are available.

If you aren't sure which (if any) third-party plug-ins you have installed, choose Installed Plug-ins from the Safari Help menu.  A window appears showing the versions of each plug-in, as well as other information.  

Troubleshoot third-party plug-ins

If you're using the latest versions of any third-party plug-ins yet Safari still unexpectedly quits, try disabling plug-ins:

1. Open Safari.
2. From the Safari menu, choose Preferences.
3. Click Security.
4. Deselect "Enable plug-ins".
5. Use Safari for a while until you are reasonably certain it is no longer unexpectly quitting (or, if it still is quitting, skip to the next section).

If Safari no longer quits unexpectedly with plug-ins disabled, try to isolate which specific plug-in is causing the issue:

1. Log in to Mac OS X as an administrator if you aren't already.
2. From the Finder's Go menu, choose Go to Folder.
3. Go to this folder (type or paste the following):
   
   /Library/Internet Plug-Ins
   
   (Leave this folder window open.)
    
4. From the Finder's Go menu, again choose Go to Folder.
5. Go to this folder (type or paste the following):
   
   ~/Library/Internet Plug-Ins
   
   (Leave this folder window open.)
   
   These two folders hold third-party plug-ins.
6. Move all third-party plug-ins from these two folders to a different, temporary location, such as a new folder on your desktop.
7. In Safari, from the Safari menu, choose Preferences.
8. Click Security.
9. Select "Enable plug-ins".
10. Quit Safari.
11. Add one third party plug-in back into the appropriate Internet Plug-Ins folder.
12. Open Safari and test for the quitting issue. If Safari is not quitting, quit it manually and add another third-party plug-in back into the appropriate Internet Plug-Ins folder.
    Repeat this process until you discover which plug-in causes Safari to unexpectedly quit (then remove that plug-in from the Internet Plug-Ins folder).

Sometimes, a combination of plug-ins may cause the issue.  To double check this, remove all plug-ins again.  Then only add the plug-in you found in the above steps.  If Safari unexpectedly quits, then you have found the plug-in at issue.  If Safari does not unexpectedly quit, repeat the above steps but add the plug-in at issue at the start to discover the other plug-in it may be in conflict with.

Troubleshoot Input Managers

Troubleshoot for Input Managers as you did for third-party plug-ins above. Input Manager issues may occur after installing a new version of Safari.

Input Managers reside in these two locations:

/Library/InputManagers
~/Library/InputManagers

The steps to find an Input Manager at issue are the same as the steps to find a third-party plug-in issue as described above, except for the locations.

Reset Safari

To reset Safari, choose Reset Safari from the Safari menu.

From here you can clear history, empty the cache, clear the downloads window, remove all cookies, remove all website icons, remove saved names and password, remove other AutoFill form text, clear Google searches, and close all Safari windows.

You can do these all at once, or one at a time to try to preserve items you want for convenience.

Check Web Clip widgets

If you made Web Clip widgets, the webpage that it is the source of a clipping might be causing Safari to unexpectedly quit.  Go into Dashboard and remove any web clip widgets.  Then, if you can access the original website, re-create the widgets and see if the issue persists.

Try a new user account

Create a new administrator account in Accounts preferences.  Log into the new user account and see if Safari has the same issue.  If Safari in the new user account does not have the issue, the issue lies somewhere in your original account.  If the issue still occurs in the new user account, there is a a system-wide issue affecting your Mac.
 

Try a different ISP or Internet connection

If possible, try connecting your Mac to the Internet via a different ISP. If the issue occurs only when you are connected to a specific ISP, contact that ISP for further assistance.

For various reasons, your ISP may cache Internet connections to minimize traffic outside of their own network.  This cache can be compressed then decompressed with some alterations when the packets are delivered to your Mac. Tolerance of this may vary by web browser--third-party web browsers may respond differently than Safari.
 

Reinstall Safari

Download and reinstall Safari.
 

Reinstall the latest Mac OS X Combo OS update

Download and install the latest Mac OS X Combo Update that is appropriate for your Mac, even if you already have the same version of Mac OS X installed.
 

Perform an Archive and install installation of Mac OS X

If none of the above steps resolve the issue, perform an Archive and Install installation of Mac OS X.