I'm loving this thing, having carried the 2010 MBA for a year. I'm having one issue, however. When I close the lid and put the MBA down, and come back to use it several hours later, it won't wake up today. I open the lid, the screen light comes on (the Apple on the lid turns on), but the screen stays black. I try clicking the touchpad to wake it up, but eventually I need to hold down the power button to shut off and then restart. Any ideas?