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 document file referencing a file lock stored on the document server, wherein the file lock comprises a first file lock that is a shared lock, and wherein the first file lock permits write-access to the at least one document file by a plurality of software applications; 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, wherein the coauthoring status indicates whether the software application supports coauthoring; and a file lock processing module that stores a plurality of file locks, controls the setting and resetting of file locks, and determines a file lock status of the at least one document file, wherein the plurality of file locks comprises at least the first file lock and a second file lock that is an exclusive lock, wherein the second file lock permits exclusive write-access to the at least one document file by a single software application; wherein the document access processing module uses the coauthoring status of the software application and the file lock status of the at least one document file to determine whether the software application is permitted to have write-access to the at least one document file, and wherein the document access processing module resets the first file lock to the second file lock if the software application supports coauthoring and the at least one document file includes features that do not support coauthoring.