There are so many complex interdependencies of kernel, scripts, and permissions, not to mention the comparatively trivial issue of software versions, that it's very easy for inexplicable shit like this to happen. After being around UNIX long enough you get a "feeling" for what might be happening, and that allows you to track down the issue. To make matters even more ridiculous, the systems geniuses out there are trying to push "IPv6" - which is really "IPNG" which is really the "ping" program cleverly rearranged and amplified into system stomping alphaware. Aren't those guys clever!!!

You DO realize that the IP filtering function is now inside the kernel distribution? In SuSE you make sure that's turned on (it is in the land yacht kernel that ships with it). The VERY FIRST thing I do with a new version of Linux is rip all the BS out of the kernel by traversing every last option and turning off everything that isn't directly related to my needs and my hardware. I then track down every last error and warning and get rid of them one by one. This is a tedious, time-consuming thing, but it pays off because you can eliminate the kernel as a source of issues, and you get to know all its aspects. If IP won't start, something is badly horked about your configuration.

Doing a firewall should be easy with folkert's scripts. I'd just start over, by minimalizing the kernel and going over /var/log/messages (warn, faillog..) and the output of dmesg until all the warnings and errors are removed.

Note: a lot of issues can hide in the modprobe mechanism. Many problems get solved by properly editing /etc/modules.conf.