how to blacklist an unwanted module

Mostly in connection to a wireless card it is necessary to block some modules in the kernel to overcome kernel panic:

Note: Some people experienced random kernel panic with the new 2.6.37 because they forgot to blacklist some modules that normally had to be disabled for their Broadcom wireless card. See the wiki.
The thing is many wireless drivers are included with this new kernel so your wireless card will most likely work right away but you still have to be careful (at least for Broadcom users). If you get a kernel panic and your wireless card gets disabled, your system
might freeze with a black screen everytime until you enable your wireless card again through windoze or something else). If you used to install broadcom-wl for your wifi card, you should still install it (to be sure your wifi card works perfectly and to have a blue LED rather than a RED one)
It occured to me so I know

Blacklist the unwanted module on the MODULES= line by prefixing it with a bang (!) in /etc/rc.conf.
example:
MODULES=(!ath5k !rt2860sta forcedeth snd_intel8x0 ... ...)

roll back kernel version

For the first time I had kernel panic in Arch on old pc that seems to have some hardware issues; I could login on the fallback kernel - recovery mode, but then network wasn't working.

Found this info on kernel panic:

Roll back to previous kernel version

If you keep your downloaded pacman packages, you now can easily roll back. If you didn't keep them, you have to find a way to get a previous kernel version on your system now.

Let's suppose you kept the previous versions. We will now install the last working one.

First you need to get the kernel details.

# cd /var/cache/pacman/pkg
# find kernel*

Now use the kernel details in the command below.

# pacman -U /var/cache/pacman/pkg/kernel26-2.6.23.xx-x.pkg.tar.gz


More info here:https://wiki.archlinux.org/index.php/Kernel_panic