I hope someone can shed some light on a seemingly weird issue. I recently got a 2010 Mac Pro and decided to set up Boot Camp and Windows 8.1 on a separate hard drive that I popped in. Started Boot Camp Assistant in El Capitan and went through the process just fine. Got into Windows, downloaded updates, rebooted, installed more updates, rebooted, etc. Everything is going good. Then I decide to boot into OS X and then the machine restarts. Chime sounds, screen is white, but shows a crossed out circle. I mutter bad words to myself, and after several seconds, the crossed out circle changes to the Apple logo with the bar filling up. Gets into OS X just fine. I figured that was weird, so I logged in and restarted. Crossed out circle pops up again, and after several seconds, shows the Apple logo and loads up fine. In OS X I check Startup Disk under Preferences and there are two drives listed, OS X and BOOTCAMP, both of which are ghosted out. I select OS X and save the changes. But after rebooting again, the machine does the same weird boot sequence again and Startup Disk preferences won't "save" whatever disk I select. I mean it's not like I can't boot into whatever OS I want, I can, it just is weird that this crossed out circle pops up and stays there for several seconds before eventually deciding to boot OS X. Any ideas what could be going on here or how I can rectify this? If additional details are needed, let me know, thank you.