I have a Mac Mini Mid-2010 running Lion. My computer has twice suddenly changed the display to a lower resolution. The screen looks stretched and everything is pixelated. Both times, it occurred sometime during or before sleep. I couldn't get it back to it's regular resolution the first time. I left if off for a weekend and after turning back on, it went back to normal. Now it just happened again. Any ideas? I've already tried changing cables and such. The screen is a Viewsonic Optiquest q201wb connected via VGA.