net connection problems

[navaja <cantinho@myrealbox.com>]

hi everyone,

when i boot debian, my net connection is up, and i can browse the web 
fine, ping hosts,etc.
after a  few minutes, i lose the connection. i cant ping external ips i 
can only ping my router. i cant even acess the http server on my router.
ipconfig reveals no clues as to what is going wrong as everything seems 
fine.

routing seems to be the same, before and after the network connection 
stops working, as the output of netstat -rn is the same in both cases.

i can use the same host fine when booted into XP

thanks