My sister called me today to tell me about a problem she is having with her computer. I don't know what it is. I'm hoping someone here does. -Powerbook G4 -When it turns on the screen turns gray and then the computer makes a really loud continuous buzz/hum. She held it up to the phone - and it didn't sound good. -She said the problem came on suddenly. -She also said she didn't turn it on for about a month. Then turned it on and it was working fine for a couple minutes then when she was in iTunes it froze and started making that noise. She left it on to see what would happen and she said the screen turned into a small square in the center and froze. Anyone know what is wrong? Thanks.