MacOS Automount NFS – Stop OS X From Auto Connecting to NFS Server

I upgraded to Lion today, but was having the same problem on Snow Leopard. When I start up my Mac and login, it automatically connects to an NFS server. I know this because I see the server in Finder in the Shared section. I'm assuming I connected to the server at some point in the past, but I'm not sure how to make it stop connecting now. Where can I look? Even after ejecting the server, it reconnects on the next startup. What can I do to make it stop?

Further information – here's what my /etc/auto_home looks like:

#
# Automounter map for /home
#
+auto_home  # Use directory service
#
# Get /home records synthesized from user records
#
+/usr/libexec/od_user_homes

And running /usr/libexec/od_user_homes produced no output.

The mount doesn't show up in Disk Utility or the Directory Utility, and running lsof doesn't show the mount (/CIFS). df does show /CIFS and indicates that the Filesystem is x-browser:

Here's /etc/auto_master:

#
# Automounter master map
#
+auto_master        # Use directory service
/net            -hosts      -nobrowse,hidefromfinder,nosuid
/home           auto_home   -nobrowse,hidefromfinder
/Network/Servers    -fstab
/-          -static

And the output from mount:

/dev/disk0s2 on / (hfs, local, journaled)
devfs on /dev (devfs, local, nobrowse)
map -hosts on /net (autofs, nosuid, automounted, nobrowse)
map auto_home on /home (autofs, automounted, nobrowse)
x-browser: on /CIFS (nfs)
localhost:/gWMIVnK_1WG9ZzUq0q3qb7 on /Volumes/MobileBackups (mtmfs, nosuid, read-only, nobrowse)