Very odd problem, so my expectations on solving this are low!
On my laptop (not desktop), my log in items are disappearing, after they are up.
ok just to make sure I am understanding this correctly, your login items are launching at login, but are quitting unexpectedly. They aren't being removed from your login items list though, so are relaunching the next time you log in, but will just unexpectedly quit again shorttly after login?
Do the apps quit with 100% reliability, or do they only sometimes quit? Do all of them quit or just some? (the same ones every time?) Do you know if they quit at the same time?
What happens if you remove them from your login items, reboot, login, and launch the items manually? Do they still eventually quit on their own? How long does it take for them to quit usually?
Are you able to test with another account to see if the same problem happens for other users also?
Is it possible that the apps continue to run until you do something specific, like launch a specific application, put the computer to sleep, let the screensaver come up, have a calendar alarm come up, etc?
