Wireless - Limited Connectivity

Just purchased a Inspiron 6400 complete with Windows Vista and a Netgear N router.  Inernet connection works fine when I am hard wired through the router but I am having problems when I go wireless.

 

I can set up a secure wireless connection encrypted with WPA2 / AES security, connect to the wireless network, go online, check email and everything is great...until I turn of my laptop.  When I turn on my machine again my wireless network still exists but it has 'limited connectivity' and zero internet access. 

 

I have spoken with Netgear support and they insist it is not a router issue.  Their experience suggests a operating system problem or system setup issue.

 

Does anyone out there have any insight.  It would be greatly appreciated.

 

Cheers.