I think i might know what the problem is.
I have had similar problems for a few weeks now on my Dell computer (Brand New).
If you can understand whats below then go ahead and do so but, if not find someone who does...
1st Disable all adapters. (Do this by going to Network & Sharing Center then click on Manage Network Connections).
2nd Re-enable wireless adapter only.
3rd Go to Network & sharing center
4th Click on Manage Wireless Networks
5Th Highlite your adapter and remove (close page).
6th Back to Network & Sharing Center click on connect to a network.
7th Connect to your Network.
Then you should see that your connected to the internet. But...
When you try to re-enable LAN adapter you may have the same problem as i have which is that, it automatically tries to connect to a Network and then for some reason which i know not of, it locks out the internet. So in my case i leave the adapter disabled.
Best of luck and i hope someone may find a solution to our problem.