So I updated my Mac Pro to 10.6.5 and went along my merry way doing Mac stuff. I noticed after start up I'd get a message that a disk was unmounted without ejecting and there is a risk of data loss, yadda yadda. Turns out my oldish (2007?) Western Digital My Book Essential external hard drive are unmounting themselves after about 2 minutes of being connected. I reconnected the drives (unplugged then plugged in the USB) and they unmount by themselves a few minutes later. My Mac Pro can see the drives while they are mounted, but can't access any of the files. I move the drives over to my MacBook running 10.6.4 and the drives have no problems staying mounted and working. I searched for updated drivers, etc. but can't find anything. Has anyone else experienced this? Is there something that can be done or do I need to remain patient and hope Apple or WD fix the problem? The data is backed up, but I'd hate to lose 1 TB worth of disk space. I may try to reformat one in 10.6.5, but I shouldn't have to do that - and it may not work. Any thoughts?