My system drive recently failed and so I installed on a another drive in my mac pro. I've taken the other (failed) drive out. My current system drive which works great so far when my computer is booted up and running, is not found automatically during start up. For example, if I restart the computer it will either show me a blank screen forever, sometimes a missing folder, sometimes nothing. But if I hold option during start up, sure enough the system drive will show up and I can go on my way with no problems. I've checked the startup disk in the prefs and it is indeed on the correct drive. I'm not really sure what else I can do. any ideas?