DNS resolution problem with cisco vpn concentrator

Any hints welcome. After migratin form NT4 domian to Windows 2003
domain, I have found that our Cisco VPN concentrator is now unable to
access mapped drives by UNC; I just receive an access denied error.
However, if the server name is replave by its IP address then the
mapped locations are accessed normally with the correct security
settings etc. I have confirmed with Cisco that the VPN settings are
correct. My DNS server is working correctly and I have 2 WINS
replication partners functioning normally. All servers are pingable
from the VPN concentrator by name and IP address. I suspect an IPSec
policy setting possiblt or PP2P protocol issue but am unable to find
anything.

Any help is appreciated

Thanks