I have a mac powerbook G4 that froze while i was working on a word document. force quit would not work and the only way i could get the computer to turn off was by holding down the power button until it turned off. so once it was off, i tried to turn it back on... but now it won't get past the start up screen - the grey one w/ the apple sign. im worried that i've lost that document and i dont want to do anything to make it worse. what should my next step be?