whilst in VPN cannot see other PCs on network

[chrisbirley]

I use multiple VPNs at work, solving customers problems and performing morning check lists, but until recently i have been fine connecting to the companies via VPN and using VNC, but now i am unable to see any of the PCs, i have a piece of software that scans IP addresses, but this does not display any of the other machines except for my PC twice, once as the server and once as the client, it doesnt even show the ADSL router! i have tried using other PCs and they are fine, so it appears to be my PC, but i am lost as to what it might be as it is only some of our customers that i cannot connect to properly.

HELP