My computer has a problem with slowing down. When I boot up, all runs well. However, after it's been running for awhile, it starts to slow down. For example, when I try to get into folders, it will take a loooooooooooong time to open the folder after double clicking on it. Like I said, upon initial boot up, it runs fast, but slows down after the computer's been running for awhile. When it starts doing this, I can reboot and all runs well for awhile. Please advise...thanks.