For the past several months, I’ve had a disconcerting issue with my iMac. The iMac randomly tries to log me out. My old Mac Mini, which has been retired to the household media server, never had this problem.
Googling the symptoms resulted in a mixed bag of possible causes: failing hard drive, faulty memory chips, logic board problems, etc. I looked on the Application > Utilities > Console application for any log files that might indicate a sudden quit, logout, or restart command. Nothing. At least nothing consistent or obvious. Tech Tool Pro did detect some serious hard drive issues. According to Google, the symptoms my iMac had could be caused by a malfunctioning hard drive.
Back in November, I received an email from Apple stating that my iMac model was suspected of having a faulty Seagate hard drive and Apple would replace it for free. The hard drive replacement was scheduled over the holidays so I could get my Mac back and then restore the data using the Time Machine backups. (That is another story all together.) If the random reboots and logouts were caused by hard drive issues, then replacing the hard drive should theoretically fix the problem.
I got my system back a few days ago, restored the primary partition using Time Machine flawlessly. However, the second partition with my working data didn’t restore cleanly. I kept getting permission errors. I’ve spent the past two days manually restoring files from the Time Machine backup files. It’s now back to normal. Except my old 1TB Time Machine drive didn’t have enough space to complete a backup. I wasn’t willing to delete the only backup I have, so I bought a new 2 TB Time Machine drive today.
The bacukp has been running for over two hours so far. Twice, I’ve come back to check on the backup and have found that the system had tried to log me out and quit running applications. (Luckily I learned that leaving Safari open with multiple tabs prevents a log out because Safari prompts if you really want to quit the application.)
I did some more searching and discovered a setting I didn’t know about from a posted question and answer on the Apple Support Communities. The System Preferences > Security panel has an option that says “Log out after 60 minutes of inactivity.” This option is checked by default. I’ve unchecked the option now.
I’m leaving the system on over night (to hopefully complete the backup) and then will post whether or not the system tries to log me out again.