Actually I've seen the arp problem as well. What arp entry do you have
for them? We have:
mae-west.netcom.net (198.32.136.15) at 0:0:c:61:b:0
If yours is different, you could try deleting it and if it still comes
back wrong, you could try temporarily adding a static entry. Are either
you or netcom connected through a netedge?