FreeBSD's sysinstall jacked rc.conf:

default

After using sysinstall to reconfigure ip address system may hang on boot with this error.

Trying to mount root from ufs:dev/ad0s1a
/etc/rc.conf: 40: Syntax error: Unterminated quoted string
Enter full pathname of shell or RETURN for /bin/sh:

After choosing shell type:

mount -a -t ufs

This will mount the filesystem with read/write.

Open /etc/rc.conf with an editor and look for an unclosed quote, misMatch single and double quote, or \ before "

Example of appended data to rc.conf with \ as error

# -- sysinstall generated deltas -- # Tue Oct 10 00:42:02 2006
ifconfig_bge0="inet 192.168.1.115  netmask 255.255.255.0"
defaultrouter="192.168.1.226"
hostname="ishbsd.houston.rr.com"
# -- sysinstall generated deltas -- # Sat Oct 14 17:31:21 2006
ifconfig_bge0="DHCP"
hostname="ishbsd.houston.rr.com\"

After fixing the error type:

exit

This should boot to multiUser mode.

Restart system and make sure it's fixed

default