I saw this before..
I was helping someone in Australia and by default his DHCP / LAN / GATEWAY whatever the hell you want to look at it as was set to : 10.1.1.1
It was the same in other countries when i messed with routers. I only encountered 192.168 here in america or if i manually put it in myself.
I went step by step in this dudes router and everything and checked everything...
Sometimes it all comes down to the router... some well i shouldn't say some majority of cheap routers are not par to the new windows 7 systems.
I just tried to fix that one dudes system in Russia and it turned out to be his router... and it fixed everything.