Inspiron windows 7 network problem

I installed Windows 7 Home Premium on my Inspiron 6400 and now i have a little problem with my Internet Connection. After booting the system, i got no internet connection. My Network works fine, i can access all shares in my office Network and my laptop recieves an ip via dhcp from the router but i got no internet connection.

If i deactivate the network device in my device manager and re-activate it, then everything works fine.

Can someone give me a hint how to solve this Problem?