Loss of internet connection, but wireless still connected

Hi

Been having problems with wireless on Inspiron N5040 since purchase - wireless card is Dell wireless 1701 802.11b/g/n, access via BT Homehub 3.

Basically, and unpredictably, connection to the internet is occasionally lost, but wireless connection still shows as connected. A Restart will always restore the connection (but Disabling then Re-enabling the card will not).

I've implemented several fixes suggested on the net (mainly turning off powersaving for the card within Device Manager, and within Powersaving itself), and updated the driver, but still get the problem intermittently - and now starting up Google Earth seems to lose the connection too. Could maybe be large amounts of incoming data cause the problem?

Any help appreciated.