A few months ago, I had an irritating symptom where, after selecting to put my Mac Pro to sleep, it would immediately reawaken. As detailed in a prior Bugs & Fixes article, I had to select the Sleep command a second time before the Mac would finally stay down.
The proximate cause of the symptom was the “Wake for network access” option, as enabled from the Energy Saver pane from System Preferences. Disabling this option eliminated the symptom. This was a good enough solution for me. (The ultimate question of how to prevent the problem without having to disable the option need not concern us today.)
All was fine on this front until a couple of weeks ago when the Wake symptom mysteriously returned. Why? Because “Wait for network access” had been re-enabled. Huh? How? I certainly had not done so.
I knew that the actual setting for this option was stored in the com.apple.PowerManagement.plist file, located in /Library/Preferences/SystemConfiguration/. By checking the most recent modification date of this file, I was able to determine that the Network Access option was being re-enabled each time I restarted my Mac. But why?
At this point, I could have shifted into trial-and-error troubleshooting mode. I could have spent time making sure that permissions were correct—or deleting the .plist file altogether (forcing a fresh copy to be created)—or going through a checklist of typical repairs, such as running Disk First Aid and resetting the PRAM. However, I knew from experience that, absent any precise reason to expect such fixes to work, I would likely be wasting my time.
Instead, I turned to the number one, most important, most useful, most critical, absolute best troubleshooting tool available to the human race: The Web. I entered the phrase “Wake for network access reset on restart” in Google. The top hit was an Apple Discussions thread that contained the answer: It was LogMeIn. Yup, as I now recalled, I had installed this software around the same time that the symptom first re-appeared.
It’s not that there is a bug in LogMeIn. Rather, it’s a feature. Because the software is designed to permit remote access to your Mac, it makes sense that LogMeIn would prefer “Wake for network access” to be enabled. That way, if a remote device attempted to access the Mac when it was asleep—the Mac could wake up. That’s presumably why, in LogMeIn’s Advanced Preferences, there is an option to “Enable Wake On LAN.” As I discovered, this option forces “Wake for Network Access” in Energy Saver to be re-enabled on restart. The LogMeIn option is turned on by default.
After I unchecked the LogMeIn option, my wake-immediately-after-sleep problem was once again gone.
The moral of the story? You too can be a troubleshooting expert. No experience necessary. Well, almost no experience. In most cases, the quickest route to a solution for your problem is a well-crafted Google search.
Follow-up: Two weeks ago, I noted a potential wake-from-sleep display problem with the new MacBook Airs. At the time, I said “No solution has been reported as yet.” That status has changed. According to a new Apple support article, updating to Mac OS X 10.6.5 resolves the issue.