The other day, I launched iChat and it froze almost immediately. The spinning beachball persisted until I force-quit the program. Upon relaunch, iChat froze up again. This had never happened before.
A search of the Web for possible causes offered no answers. I found numerous posts describing iChat freezes and crashes, but none that directly applied to my situation.
What to do? Launch Console. It’s not the most user-friendly tool in a troubleshooter’s arsenal. But, with a bit of luck, you’ll find a message that starts you down the road to a solution. That’s what happened with my iChat freeze. A Console message reported that an item named iSightAudio.plugin, located in the /Library/Audio/Plug-Ins/HAL folder was missing.
As iChat uses my iSight camera for video (and even audio) conferencing, I reasoned that this could clearly be related to the freeze. To test it out, I disconnected the camera from my Power Mac G5. Sure enough, iChat launched without a hitch.
Of course, this was not an ideal solution, as I was now without a camera. I assumed that a better solution would be to locate the missing file and reinstall it. I checked my MacBook Pro for the iSight file. And there it was! While there is some risk in transferring a Library file from one Mac to another (as different Mac models may use different versions of the same file), I took a chance and copied the file from my MacBook Pro to my Power Mac.
Total success. iChat launched successfully even with the iSight camera reconnected.
But what if you don’t have a second Mac from which to grab the missing file? If you use Time Machine, or any similarly functioning backup utility, the file may still be there.
Otherwise, you can re-install the needed file from your original Leopard Install DVD, using Pacifist. There are some risks with the Pacifist method. Most especially, there may be a newer version of the missing file, installed as part of a 10.5.x update that is already running on your drive. In the case of the iSightAudio.plugin, despite some oddities I found in the listed version numbers of different copies of this plug-in, the item appears unchanged since the release of 10.5.0. So the Pacifist approach should work.
To use Pacifist here, first make invisible files temporarily visible in the Finder—via any of several freeware utilities that can perform this trick. Next, go to the System/Installation/Packages folder on the DVD and open the Essentials.pkg file in Pacifist. Finally, locate the iSightAudio.plugin listing and click the Install button in the Pacifist toolbar.
As to how or why the iSight plug-in went MIA in the first place, I have no idea. While I certainly don’t recall moving the plug-in, it may have happened inadvertently when I was fiddling with audio plug-ins on a prior occasion. Otherwise, some mysterious bug was at work.