OSS and kernel panic on FreeBSD

I installed OSS driver from ports and added this line to /etc/rc.conf:

oss_enable="YES"

Now, my system won’t boot at all. It shows kernel panic while booting, dumps core and reboots. I tried booting into single user mode and correcting loader.conf but it isn’t allowing me to save the changes saying “Read only filesystem”.

The panic happens because /dev/sndstat already exists. There are two
things why this happens on FreeBSD 9.0:

1) Sound support has been enabled by default on amd64 and i386
(r222980).

2) make_dev(9) can detect attempts to create duplicate devices on FreeBSD 9.0.

First of all you should repair your system. Boot in single mode and run:

mount -u /

If you use zfs file system run commands:

# mv /etc/rc.conf /etc/rc.old
# echo 'zfs_enable="YES"' > /etc/rc.conf

If you doesn’t use zfs you can run:

# mv /etc/rc.conf /etc/rc.old
# echo '' > /etc/rc.conf

Then reboot your system and comment this line in /etc/rc.old:

oss_enable="YES"

And replace contents from rc.old to rc.conf.