PPTP linux server - Linux clients ok - Windows client can't connect to some web servers

view full story

http://serverfault.com – I have one mysterious problem with our VPN office server. I have installed PPTP server on Debin 6 Squeeze and enabled forwardind, because I need to connect to some servers with our office IP address. Everything works like a charm when I am connecting from Linux client (Ubuntu and Android). I can access office server and services on this server and I can connect to all server on the internet with my office IP address. But when I connect from Windows client (test XP and 7), I can access office server and services and only some servers on the internet. Ping works to every servers, but I can acces (HowTos)