Any suggestions as to what is happening here? I've been up for a week on Lion. Use it a lot in my work travels. Just shut it down for landing at my short layover. Got in the terminal to wait for my next flight and I got a "no symbol" and a spinning wheel. I made a USB for installing Lion and used it to boot into Disk Utility. First I tried repairing permissions. There were quite a few repairs, but it's the first time I've run this. Still no boot. Rebooted into Disk Utility and did a disk repair. Even though the disk check said all was OK, I can now boot into regular Lion. Any suggestions or explainations?