I've got both my MacBook Pro and Mac pro connected to the same monitor and keyboard via a switch. While using the MacBook Pro, rather than going to sleep, my MacPro continually stops and starts it's hard disk making the same noise as when the machine boots up and closes down. It's like it goes into a continual look (the computer isn't rebooting itself though). The continual whirling sound in the background drives me nuts. Any one know how to stop this?