VPN Allows Outlook but no Network shares access

Server is Windows Server 2003 SP2. Laptops are XPSP2. VPN will not allow access to shares – says drive is disconnected, or not available, or even ‘possible attempt to compromise security’. VPN verifies, Outlook connects and updates, and not all users experience issues. Have checked permissions to shares, even deleted and recreated shares. Gave all users Domain Admin privs and still didn’t correct. Rebuilt the VPN policies. ??