I think this is caused by a MS Networking glitch. You probably have your computer configured with two network cards, and each of them has a default gateway address. The computer chooses at random between them, or chooses by the shortest path. I've found that tis usually causes the computer to choose the wrong path. You can remove the default gateway from your NIC connected to your LAN, and that shoudl fix your problem. You may have to set up static routes in your computer for your lan stuff.