I had a problem where I had taken a drive out of /etc/fstab, but it was still mounting on a reboot. I finally traced the problem to the haldaemon and fstab-sync. My understanding is haldaemon is the thing that watches for hardware changes and automounts flash drives and the like. It also can update /etc/fstab with these changes. This is something that I don’t want, so my first impulse was to turn haldaemon off. But then, if someone did plug in a flash drive, it would have to be mounted manually. After reading a bit on haldaemon, I found that I could disable the changing of the fstab file by changing a link. Specifically, I had to change the link /etc/hal/device.d/50-fstab-sync.hal from pointing to /usr/bin/fstab-sync to /bin/false.