Error copying file form Dutch XP system to English W2k3 or W2k ser

Hi,

We have having a problem copying files and mapping drives by name, to
English file servers. Here is the scnenerio
We have Dutch XP clients setup in the Netherlands. The file servers in
the Netherlands are in English.
We have a VPN setup between our Netscreen Firewalls, allowing access
both ways. There is a 2 way external trust between the domains.
In the United States, we have file servers with shares on them. The
Dutch clients can map a drive by IP address, using credentials from the U.S.
domain, but cannot map by name. They can resolve the names from command
prompt. There is a static WINS entry for the file server here. They can copy
files from the U.S. server to their local machine, but cannot copy from their
machine to the file server without getting an error stating "The network name
is no longer available". It does still copy the file, but it is corrupt. It
seems that there is something done near the end of the copy that causes the
problem.
These dutch clients can, however, copy to a share on an XP system in
the U.S. office. They just can't do it to a Windows 2000 or 2003 server.
Any help would be appreciated and thanks in advance.

Tom