I started to try out the 5.0.1 on a AMD 1 Ghz, 512 MByte with a 3COM NIC. I got a similar
picture of the network trouble as discribed by sean,1986:

a) dhcp configuration worked fine (!) with my DSL router - DHCP server combination provided
by my telecommunication supplier

ifconfig showed up the expected network address, broadcast addr and netmask

b) a ping to the DHCP server failed: host unreachable message.

c) dns and all other services fail

d) while observing ip traffic, I saw activieties on the loop back device while pinging (lo)

e) the 5.0.1-host is also not visible within the local network

f) I tried the full installation of 5.0.1 and did a full manual network configuration.
The malfunction is still the same.

I hope that there is someone out who can put together the dangling ends - I'm sure
the hardware is correct and I saw that the setup of the network worked correctly. The big
question is: why does everything works fine with 4.0.2 (also in my case) - is there a trick
with respect to features of the kernel or something like that (pure speculation)

Best regards