Accessing a network folder on a Win 2003 server

I manage a small network of a dozen machines all running XP that attach to a server running Win 2003.

The subject machine can access several shared folders on the server, but one folder is not accessible. It is accessible from other machine, but just not this one. I have checked everything I can think of and compared it to machines that can access it.

Can someone point me in the right direction?

Thanks in advance