Changing File Names On Network Server

When logging into the network server here, when I want to rename a file (in this case, a Quark file or .qxp) I get an error message saying "The file name can not be changed because the file is in use". However, I'm just clicking on the name in the Network section of the Finder. So the file is not open and running, Quark is not running, and when I command+I to do a Get Info, the Permissions section, which normally has the three options has only one non-changeable thing saying:

"You can read and write"

If I can read and write (I have admin status, but others using this machine would not) why was I not even able to change a simple file name? I am not able to delete or move these files from the server either. Weird stuff. Any help is appreciated.