While teaching a class on debugging your Macintosh, we ran into an issue on Elizabeth’s machine we could not fix! Activity Monitor refused to run, due to permissions.
We checked Activity Monitor and it had the proper permissions, except that the Finder claimed that there were two ‘everyone’ Access Control List Permissions. oh oh.
With a little googling I found the culprit: The pmtool in Activity Monitor.app/Contents/Resources/pmTool.
pmTool had lost it’s ‘setuid’ permissions, which allows the tool to become super user in order to change permissions.
Upon more investigation and comparing to other machines, the entire Activity Monitor application is out of date.
The solution will be to delete Activity Monitor and install the 10.5.5 combo update to check for any other issues the machine may be having. After a full backup of course 🙂
Update:
Combo updates do not contain complete applications. If you delete an application such as Activity Monitor and run a combo updater, you’ll be a broken, partially installed application.
This makes sense; It was just not known how partial updates were. The solution, to cure this and any other gotchas, was to do an archive & install, then delete the previous system folder.
All applications now have proper permissions and function as expected.