Strange Network Problem (TTL?)

[Fraser Campbell <fraser@baxter.net>]

We are having a problem reaching a specific host on another network.  The
host is unreachable from Windows desktop machines.  I thought it might be a
problem with the TTL setting on the remote system (it still might be I
suppose) but I'm not a TCP/IP expert and since the performance is so
inconsistent I am unable to draw conclusions.

>From our network:
When I ping from a Linux computer I get this:
64 bytes from 12.17.202.16: icmp_seq=0 ttl=27 time=127.3 ms

When I ping from Windows 2000 I get:
Reply from 12.17.202.16: bytes=32 time=120ms TTL=91

When I ping from Windows 98/NT on the same LAN I get "request timed out".

Other networks:
>From Win98 on Netcom dialup I can ping, TTL=9.
>From Linux on other ISP I can ping, TTL=42.
>From Win98 on AT&T dialup I can ping, TTL=11.

How can the TTL vary so much (especially on the same LAN)?  Probably I
misunderstand TTL but this seems impossible to me ...

The only service running on the remote host is VPN as far as I know. 
Hostname of this host is vpn.galileo.com.

Ideas appreciated,

Thanks!

Fraser