MN-700 (?) PROBLEM

I asked for suggestions in similar post a few days ago, but since I received
no responses, perhaps I wasn't clear or detailed enough:

My VAIO laptop with integrated wireless - g adaptor routinely ceases being
able to connect with the internet after a few minutes to few hours of good
connectivity, even though all indications are the wireless connection with
the MN-700 is is still functioning. I have done all the suggested
power-down/cycles, made sure my MN-700 firmware/software is up-to-date, to
no avail. I end up restarting the laptap which always restores the lost
connectivity. Any suggestions???

My laptop and desktop both are running XP SP2, and I keep the XP firewall
disabled. The MN-700 connects to a cable modem. When I lose internet on
the wireless laptop, the cabled connection to the desktop is unaffected.
The laptop simply looses ability to connect over the internet, even though
the wireless connection with the MN-700 remains. Again, restarting the
laptop always restores the internet connectivity, so I sure would like to
know what is being "re-set" when I restart XP. How about it you MVP's?
Got any ideas?