...or not. My iMac occasionally fails to wake from sleep no matter how much I move the mouse, mash the space bar or verbally encourage it. Requires a forced restart via the power button. I can't identify any particular activity on my part that could cause this and I've trawled a few other fora (ums?) for an answer but without success.
My Energy Saver prefpane is set for 1 hour Computer and Display sleep and all the boxes except "Restart automatically if the computer freezes" are ticked. Hmm, might tick that one too if it automatically restarts on failure to wake!
An occasional restart isn't such a bad thing but I would prefer to choose the time. I wonder if any contributors to this venerable forum have any clues?
iMac 21.5 in, late 2009, 3.06 GHz, Core 2 Duo, 8GB, Lion 10.7.1