At the school district I work at, we have 1,000+ Macs (mainly MacBooks, but a few aluminum iMacs) all running Mac OS X 10.7.4. We use Mac OS X server for open directory logins and all students have mobile homes on whichever computer they log in on. The problem we had this year was when the students tried to log in, the sync window would open up, the mobile home & server would sync, then the screen would flash gray and then go back to the log in screen. The IT guy who handles the servers and login issues found out syncing corrupts the login.keychain file. He eventually found that if we don't sync the keychains, students could log in fine. This never happened under 10.6.8. Anyone else experience this problem?