Flashing file and question mark symbol
My Mac is alternating between displaying a flashing file with a question mark and the prohibitory symbol. I tried holding down the option key after restarting but nothing is working. I updated my OSX Lion last night, but I don't know what update it was. I need this computer working in the next 3 hours. Please help!
MacBook Pro (15-inch 2.53 GHz), I updated my OSX Lion last night