Wireless connection trouble with VOSTRO 1700

I have a Vostro 1700 with a

Intel® Pro Wireless 3945 (802.11 a/b/g) MiniPCI Card.

I am linked wirelessly to a BT Home Hub.
Sometimes , after a while online , my connection drops to my router(although my broadband connection is stable).
The message reads , "CONNECTED WITH LIMITED ACCESS."
I am then unable to re-connect to the Web.

Sometimes i can be online for hours with no problems.Sometimes less than an hour.As i write this, i have been online for 4 hours - no probs.
I can't beleive that my firewall is only causing problems intermittently !

I wanted to know if maybe my Firewall is causing the problem.
I did just use the Windows firewall but when i set up my wireless connection, i disabled it as it played up when turned on.
Now i have installed Norton Internet Security which has it's own firewall.
My service provider said that my home Hub had it's own firewall built in.

Are the firewalls conflicting ?
Or is my Network card playing up ?
Does anyone know if my Home Hub does indeed have it's own firewall ?
I'd rather not go online without one.

Any advice would be of help.

Thanks.

 

Yes the homehub has its own firewall, the settings of this can be found in the advanced settings, this site is useful for info on the home hubhttp://www.frequencycast.co.uk/homehub.html but i will say that my homehub sometimes only provides limited connectivity but its usually when i first turn my notebook on, so i then reset the router and its usually alright, i havent had to reset mine in weeks now.