Just added a G-Tech mini drive to our Mac Pro to be used for Time Machine backups after out 3rd Time Capsule failed. Problem is now, when the Mac boots up it hangs on the user password login page 50% of the time and the only way to fix the issue is to pull out the Mac power cord and re-boot. The Macs are running Lion and never suffered these boot issues before. We now have the same problem on 3 Macs - all identical configurations. The G-Tech drives are connected by Firewire 800 and are not set to be bootable drives. Any idea what could be causing this? Is it possible to automatically un-mount the external drive as the machine re-boots?