I have a Mac Pro with a Intel Xeon processor and 16 GB of memory. I am running the most recent version of Snow Leopard. I have one hard drive with a bootcamp partition so that I can run windows xp for certain applications. Lately I have been having a problem with my mac freezing. It hasn't frozen on me while I am working on something, but mainly when it is sitting ideal or in sleep mode. The only way to do anything is if i do a hard reboot and shut down the system by pressing the power button. I have ran a disk utility, as well as, defraged the hard drive. I don't know if it is my hard drive, but if it is I would like to replace it while it is still functioning. Does anyone have any suggestions or know what the problem might be. Any help is greatly appreciated. Thanks.