I just installed Tiger and my computer keeps making a whirring noise. I called Apple Tech Support and they said it sounds like the noise the computer makes when it's looking for something or when a program is operating. There is not a disc in my drive. The noise has been going all day and it did NOT do this before I installed Tiger. I went to the Activity Monitor and there did not seem to be any abnormal programs running. It is taking some of my programs longer to boot up and some of them get stuck from time to time (where the color wheel starts spinning). Apple Tech support said to take it to an Apple service center. Am I totally out of my mind? Can anyone suggest why my computer is whirring? Thanks!