I’ve experienced some problems with VPN connections after installing OneCare from Microsoft. As result of diving into configuration I’ve found that there is an option under the Firewall configuration options that denies any VPN connections by default.
In order to fix this you’ll need to go to Advanced settings of Firewall and under the ports and protocols tab put the mark near the VPN networks (IPsec or PPTP) in the checkbox list as shown in the picture below.
VPN setting inside OneCare configuration
