Networks

I have 3 Vista Home Prem laptops that I am trying to map shared drive to an office pc through a Netgear router. The salesmen need to access software on the office pc. We are using Alltel wireless for internet access, Netgear FVG318 rtr and Netgear VPN client to set up tunnel to office pc which has Vista Home Premium. I can connect the VPN but it will not let me map network drives with the ip address of the pc. What am I doing wrong? I had it working for about 2 weeks then it went down. I have replaced the router and setup all configurations for VPN again. There is no server involved. Only a p2p network. All works inside the office but not through the VPN. Any help would be appreciated.