Fedora :: Argument Against Auto-mounting Of Other Partitions?

I boot several Redhat based distributions, Fedora 15, Fedora 14, CentOS, Scientific Linux, Redhat and occasionally something non-Redhat based like Ubuntu and Debian. Out of habit and preference I frequently set up partitions to be auto mounted at boot through fstab. Somewhere in time something went seriously wrong with the CentOS install. There are a ton of permission denied errors while booting CentOS (text style boot) mostly regarding shared libraries. The system will boot to the desktop and everything looks OK but some things don't work. I can't update the system because I have no network connection. I obviously can't get to the Internet or get e-mail. I can open a VT but can't log in as regular user or root.

Permission denied in both instances. I didn't make any drastic changes to the CentOS system, just minor tweaks. The culprit in my opinion is a combination of the fact that one of the other Linux systems did an SELinux relabel while booting and the CentOS partition was already mounted. Since the CentOS partition was mounted it too was relabeled. I can't prove this. If there's a way to prove it then I just don't have the skills or knowledge to do so. It's basically a theory based on what I know I've done with the several installed distributions. This is not a rant nor is it a request for help. Just a comment. An assumption, hopefully a correct assumption. The CentOS install was working flawlessly until something happened and I think that something was the SELinux relabel.