Internet connection happens delayed with MN-500

Hi,

I have a home network setup with MN-500 as the router and
a high-speed internet connection. I have one desktop
computer connected to the router through ethernet cable.
When I turn on that computer, internet is immediately
there - no problem.

I also have a laptop that is using the wireless
connection. When I turn on the laptop, it sees the
wireless home network and says "connected". Everything
seems alright. However, the *actual* internet connection
does not show up for at least 2 minutes. For instance, I
can not browse any websites within the first 2 minutes.
Then all of a sudden, I can start browsing when the first
2 minutes is over.

I know for certain that the problem is not on the laptop.
Because if try to use my neighbour's open wireless
network (shhh!) I get the internet connection immediately.

My neighbor has unsecure network. Mine has 64 bit
encryption. The firmware is latest on MN-500 and I have
DELL Latitude D600 as the laptop.

Any suggestions, recommendations are very welcome.

Thanks,
Serdar.