Have you tried looking at your connections setup? I had something similar, although not exactly, happen on my tablet. Go through the connections setup and when you get to the last page, there is an Advanced button. Check out the IP Addresses tab. For whatever reason, when Auto-retrieve IP address was checked off, I couldn't get a proper connection, even though it used to work. I unchecked that box and just manually entered the IP addresses and it fixed the problem for me.

Hope it does the same for you. Let us know how it turns out.