Windows – PPTP linux server – Linux clients ok – Windows client can’t connect to some web servers

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 access only some of them.

Here is my config files:

pptpd.conf:

option /etc/ppp/pptpd-options
logwtmp
localip 192.168.0.2
remoteip 192.168.0.10-20

pptpd-options

name pptpd
refuse-pap
refuse-chap
refuse-mschap
require-mschap-v2
require-mppe-128
ms-dns 8.8.8.8
ms-dns 8.8.4.4
proxyarp
nodefaultroute
lock
nobsdcomp

Thanks for your help…