Good tip from os x daily.
Reset the SMC of a MacBook or MacBook Pro’s with detachable batteries:
* Shutdown the MacBook/Pro and remove the battery
* Disconnect the power adapter, hold the Power Key for 10 seconds
* Release the power key and reconnect your battery and power adapter
* Turn your Mac on
* Let boot as usual.
Reset SMC of a MacBook or MacBook Pro’s with an internal battery:
* Shutdown your MacBook/Pro
* Connect the power adapter to your Mac
* On the MacBook/Pro’s keyboard, hold down the Shift+Control+Option keys and the Power button at the same time
* Release all keys and the power button at the same time
* Boot your Mac as usual
Reset SMC of an iMac, Mac Pro, Mac Mini:
* Shut down your Mac
* Disconnect the power cord
* Press and hold the Mac’s power button for 5 seconds
* Release the button
* Reattach the power cables and boot the Mac as usual
original post here: http://osxdaily.com/2010/03/24/when-and-how-to-reset-your-mac’s-system-management-controller-smc
