Cheers,
I upgraded to 10.5.8 today and my ethernet network is broken.. but it's not so simple:
DNS works (UDP), and I can ping(ICMP). But if I try SSH, http, or other higher level TCP connections, I get nothing after an initial response. Meaning, if I watch tcpdump, I'll get an initial single packet response, but somehow the TCP session dies right away. SSH connections never connect, urls in a web browser just say "Waiting for foo.com...".
So.. any ideas? /var/log/system.log is clean.
I was trying various boot options and com.apple.Boot.plist things, but I'm rather new at that, and am not sure if I'm doing it right. I was able to fix my UUID problems during this time, though, by adding a UUID.kext.