My computer froze on me twice in one day. Once when I was using VLC, the mouse would not respond and the screen just froze on the video. The second time it happened, it was using Firefox. I could move the mouse, but the browser, and menu bar would not respond to the mouse. Without knowing any other tips, I had to reboot by holding down the power button. Is this considered a crash, which the Mac OS should experience. Can anyone suggest what may have caused it to happen? The computer is 2 months old.