I have had my mac pro for around a month now and lately most times when i boot up it takes an unusually long time to boot (a few minutes) and when it finally comes to my desktop i can move the mouse around but it wont respond to a click or any keyboard commands. if i reboot a few times it eventually boots normally, and i have tried removing all usb devices and the problem still occured. any ideas on what it is or better yet how to fix it would be appreciated