10.6.2 changing and not respecting plists?

Question

This past week a couple of strange things happened. On my iMac 20" with 10.6.2 clean, yesterday my login items list was abbreviated on startup - only a few of my menu bar items loaded. I opened the com.apple.loginitems.plist, with (a number of ) plist and text editors, and indeed, half the items normally in there were gone, as depicted in the Accounts Prefpane.
OK, weird, but easy to fix - I'll go back a couple of days in TimeMachine and replace the plist file, which I did. I opened the plist file, checked the full complement of login items were there, and did a restart. Came back up - still with the abbreviated list! OK, so replaced the plist file again, locked it, ran YASU and did a whole cache and permissions repair etc, and restart. Came back up with the same abbreviated list! Check the plist file - still locked, still complete with all items!
So I unlocked it, restarted again, it came back up abbreviated list - and changed the plist file back to the abbreviated list! So I manually added back in, (or reinstalled as the case may be), the various items as in my complete list of login items, and restarted, and now it came back up complete as expected.
My question here is: is there anywhere else that controls the login items such that would cause the above behaviour? Is there some obscure cache that overrides plists-in-place? And why was the restored plist file ignored?
Second thing happened today on another machine - Mac mini, 10.6.2 upgraded. Today one bookmark folder of Safari bookmarks disappeared from my wife's Safari bar. Five folders of bookmarks were there as they were last night, but the sixth folder was gone. The Safari bookmarks plist file was indeed missing them, but perfectly formed nonetheless. So I go back into TimeMachine and restored the bookmarks.plist file. Anyone who's ever migrated Macs knows it's just replace the file, launch Safari and voila! Not in this case. Relaunching Safari with the replaced bookmarks brought up the abbreviated list!. Cleared caches, reset Safari, repaired permissions etc etc. Checked the list in editors - the sixth folder of bookmarks is there!, but not in Safari! I then used Firefox to File > Import Safari bookmarks, and it was there! I then had to import it back into Safari for it to pick up the sixth folder of bookmarks.
Again, I don't have any explanation for any of this.
My questions are: what's causing these random cut-offs of content of plist files without corrupting them as such; and secondly: why are TimeMachine replacement files not being read or respected? Is it a Mac OS X 10.6.2 issue, or does something happen in TimeMachine that renders the restored files invalid, thus rendering a TimeMachine backup as worthless?
Message was edited by: Don Hayes

Answer 1

I too have the same issue (of Snow Leopard not respecting plist since the 10.6.2 update). In my case, custom launchd agents that ran fine before the update haven't run since; I have checked the Console and get permission denied errors when trying to run a custom launchd that calls an AppleScript application that then backs up a networked drive if the watched folder's last time of change differs from the previous backup. Also, new custom launchd agents will not run (with the same issue of permission denied errors). I have even gone sofar as to:
1. migrate a launchd agent from being a User Agent to a User Daemon, updated the time (which I originally setup as a everyday occurrence, set to run at 7:00am; it was saved as such; but the plist file, when checked, at 9:30pm (21:30h) as the time for implementation and I can't correct it, after many attempts) and rebooted, to no avail.
2. re-installed the 10.6.2 combo updater; again, to no avail
I have also repaired privileges, attempted to create new User Agents in a second Admin account, and all to no avail.
I don't know how to fix this and have search the net for assistance, again, to no avail.