For several months, my MBP has not been sleeping or waking properly. It will stay on when I close it or tell it to sleep, running the battery down as the fans continue to quietly spin. If I try to wake it up, nothing happens (even if the battery is charged), and I have to do a hard shutdown by holding down the power button.

I took it to the Geniuses twice, and the first time they said it was a major hardware issue and would need to be serviced. They tried booting from a FireWire drive and the MBP wouldn’t recognize it at all. I wasn’t ready to send it in, since Thanksgiving weekend was coming up and I didn’t want to be home for four days with no computer.

The second time, a few weeks later, I couldn’t get my MBP to replicate the problems for the Genius. Of course it works fine when I’ve spent an hour lugging it down to the mall and waiting in line. I probably looked stupid to the Genius guy, who was very nice but said he couldn’t send it in unless he could see it fail. Fair enough.

I’ve been tolerating this problem by just leaving it plugged in and turning the screen brightness to zero with Caffeine enabled, or shutting down if I’ll be AFK for a while. But a season of travel is upon us, and it’s a pain to use a laptop on the go if you can’t use sleep mode. Time to get this problem fixed.

Today, I thought I might be able to send it in from home via FedEx rather than take it back to the mall, so I visited Apple’s support section to look for a way to do this. While on Apple’s site, I searched the help files for the MacBook Pro, and came across this document on resetting the system management controller.

Was this the solution to my problem? Happily, yes. All I had to do was shut down, take out the battery, unplug, and hold down the power button for five seconds. Problem solved - now my MBP sleeps and wakes perfectly.