bat file access denied on nt server

I have a batch file which is a simple xcopy of files from a workstation
running xp pro to an nt server on our domain. Every time the batch file is
run, the file copy fails with "access denied". If the user on the same
workstation simply uses explorer and highlights and drags the files to the
server, it works just file. I have given the user full rights to the folder
she is copying to but I am assuming I am missing something in giving her
rights to copy by using a batch file. Any way to solve this apparently simple
problem. The user on the xp workstation is logged in as a user on our nt
domain. I would like the batch file to work as I am not sure I would trust
the user to drag and drop the correct files.

Thanks.