Firewall install with Guinness

["John Jones" <johnj mindquake com>]

Having trouble getting any routing to work on this 7.0 box.  I can't ping the
gateway at all, am getting "Destination Host Unreachable".  I plug in a windows
box and can ping it just fine.  The ethernet cable tests out good.  And I can
ping the interfaces (both the internal and external) just fine.  I just can't
reach the gateway.

firewall-config shows everything completely open, no rules.

Route -n shows one Gateway entry, plus one entry for each interface.

Any ideas?  Tests?  Questions to help us resolve this?  3 of us are stumped.