After my iMac has been in sleep mode for several hours, when awakening, a white screen with several gray bars at the bottom appear. The bars are highlighted in sequence before the desk top appears. After that everything works fine. Why does this happen
After my iMac has been in sleep mode for several hours, when awakening a white screen with gray bars at the bottom appear. The bars are highlighted in sequence and then the desk top appears. Everything seems to work after that. I ran the Apple Hardware test and everything was OK. Any one know what is going on?
iMac, OS X Mountain Lion (10.8.5)
