Windows 7 No Internet Access On Wireless Network

my primary source of internet at my house for the passed year is an at&t 3g usb modem (sierra wireless lightning), becuase i live in the middle of nowhere (only other option is satellite). Up until now i've been using a wireless ad hoc network to share the connection with multiple computers. I just purchased a cradlepoint router that is compatible with my usb modem so I can have a "real" wireless network in my house. I set it up yesterday and so far its working great, I have a wii streaming netflix, an android tablet, an iphone and two laptops (running vista, and win7 respectively) currently connected. The problem is my 3rd laptop, also win7. It is my primary computer that I use for business and absolutely essential that its connected to the internet. It (seems) to connect to the wireless network just fine, but gives me a "no internet access" error.

This laptop will connect to other wireless networks: it always connected to the ad-hoc, it will connect to my wifi at work and the network at my boyfriends house, also i just tried it with the verizon 3g mobile hotspot app on my droid and it connected right away. It also works just fine with a wired connection to this router (ethernet). I'm not sure where to start since every other device in my house is working with this network and this laptop will connect to other wireless networks.

ps/ Going through the windows onscreen troubleshooter it will either tell me "there is a problem with your broadband modem" or "There is a problem communicating with DNS server" (but it wont fix it)... and after going through endless google searches, i've done everything thats been suggested so far (making sure dhcp is enabled, powercycling the router/modem, updating drivers, ipconfig release/renew, disabling the firewall).