What I would do at this point is reconfigure the networking on your main PC so that the IP address of the interface connected to the modem is 67.45.30.126 (yes, 126), with a netmask of 255.255.255.252. (You might also have to set your DNS servers to 66.82.4.8 & 66.82.4.12.) Write down how it's configured before you change it so that you can change it back.

WARNING: If what I'm thinking is correct, this means your PC will be directly connected to the internet and accessible by anyone, which is bad, since you're running Windows. I'd leave it set up like this for as short a time as possible. Also turn on the firewall option in your network settings if it isn't already set that way.

Once you have it set up like that, make sure you can access web sites. If you can, try your VPN client again.

Then let us know. You might want to go ahead and reset your network settings.