Unable to access files over network

For some reason I am unable to open MS Publisher files
over my home network. All other types of files work
fine, but the publisher files give me an error message
saying "file is locked because it is currently being used
by another program. Please close the other program and
then try opening or importing the file again." The
problem is that there is no other program open on any
other computer. Any ideas or help would be much
appreciated... Thanks