1. A system for controlling access to document files on a document server, the system comprising: one or more document files stored on a document server, at least one of the document files referencing a file lock stored on the document server; and a document access processing module, the document access processing module comprising: a file sharing processing module that determines a coauthoring status of a software application of a client computer requesting access to the document file; and a file lock processing module that stores one or more file locks and that controls the setting and resetting of file locks; wherein the document access processing module uses the coauthoring status of the software application and the file lock status of a document file to determine whether a software application is permitted to have write access to the document file.