Offline Files and VPN

Windows offline files over VPN depends on IPv6.

See this guys post for evidence:
http://thommck.wordpress.com/2011/02/08/offline-files-versus-vpn-a-k-a-the-case-of-the-missing-work-online-button/

Troubleshoot a Cisco VPN

Good Cisco VPN troubleshooting checksheet
http://www.cisco.com/en/US/products/ps6120/products_tech_note09186a00807e0aca.shtml