VPN unreachable in the host when Virtual Box starts

[bruno.oliveira]

I'm using VirtualBox 4.1.22 on a Windows XP (32bit) host, with a Debian distro (32bit) guest OS.

The VPN client software that I'm using in the host (Windows XP) is the software that come with the windows.
Everything work's fine and I can establish the VPN connection with success.

When I start the Virtual Box, I can't establish the VPN connection. I don't understand why.
The network card that I'm using in the Virtual Box it's configured in Bridged mode (it's the only way, that works for I access to it).

Anyone have ideas?