Strange arpwatch message

[Omar Al-Siaghi <alsiaghi@mac.com>]

Hello all,
  We are running arpwatch on our server to monitor IP's and MAC 
addresses.  For the past day I have been having a strange problem.  I 
get this following message from syslog and daemon.log :
arpwatch: ethernet mismatch 82.150.37.41 0:3:93:d3:c5:6a 
(0:a:cd:9:73:c) eth2

While the first MAC address is my PBook's Mac address that I never 
connected with this IP address, the second MAc address is a routers MAC 
address.  And the problem is that the internet is not working thought 
the router.  Could arpwatch be causing this?  While I don't see why, I 
just can't figure out how did arpwatch get my Laptops MAC address and 
associate it with this IP if I never connected with it?

On the same problem, what could cause that I can't connect to the net 
through the router?   Everything was working fine, one day it decided 
not to work?

Thanks for the help in advance...