No internet after windows

[nuttzy]

Ok i have fully working dual boot (OS X and windows xp) computer. Only 1 thing annoys me. When i shutdown windows and go to the leopard, there is no internet. I have to disconnect power cable for 10s. And then boot to leopard. After going from leopard to windows everything is fine.

P.S. In system preferences>network ethernet shows that it is connected.
P.S.S. i am in LAN and internet is shared through server.

Anyone could solve this ?