ZyWall 50 firewall

Hi,

We have a ZyWall 50 router. From a client laptop behind this we are
trying to make a VPN connection to a remote server. When the
connection attempt is made we get an error 800 on the laptop.

When I check the router logs there is an error I reckon is related to
this:

Packet without a NAT table entry blocked: ICMP(type:5, code:1)

This error is logged every time we try to connect using the XP VPN
client. This worked a few weeks ago, and nothing I can think of has
been changed on the router.

HAs anyone got any idea what could be the problem?

Thanks,

Gary.