A method for accessing a file in a directory structure associated with an application, the method comprising: (a) intercepting , by a filter driver executing on a computing machine , a first request for access to a file by a first application executing within a first isolation environment including an application isolation layer and a user isolation layer ; (b) redirecting , by the filter driver , the first request to the first isolation environment ; (c) determining , by the filter driver , that the file does not exist in the first isolation environment and that the file is in an enumeration of a directory structure including a plurality of application files residing on a remote machine ; (d) redirecting , by the filter driver , the first request to a second isolation environment including an application isolation layer and a user isolation layer, responsive to the determination that the file is identified in the enumeration of the directory structure ; (e) determining , by the filter driver responsive to the determination that the file is identified in the enumeration of the directory structure , that the file does not exist in the second isolation environment and, in response, retrieving, by a transceiver on the computing machine , the file from the remote machine and storing the retrieved file in the second isolation environment; (f) responding, by the filter driver , to the first request with the retrieved file; (g) intercepting, by the filter driver , a second request to access the file made by a second application executing in a third isolation environment; (h) redirecting, by the filter driver , the second request to the second isolation environment, responsive to the determination that the file is identified in the enumeration and that the second isolation environment contains the retrieved file; and (i) providing, by the second isolation environment, the second application with access to the retrieved file. (a) intercepting , by a filter driver executing on a computing machine , a first request for access to a file by a first application executing within a first isolation environment including an application isolation layer and a user isolation layer ; (b) redirecting , by the filter driver , the first request to the first isolation environment ; (c) determining , by the filter driver , that the file does not exist in the first isolation environment and that the file is in an enumeration of a directory structure including a plurality of application files residing on a remote machine ; (d) redirecting , by the filter driver , the first request to a second isolation environment including an application isolation layer and a user isolation layer, responsive to the determination that the file is identified in the enumeration of the directory structure ; (e) determining , by the filter driver responsive to the determination that the file is identified in the enumeration of the directory structure , that the file does not exist in the second isolation environment and, in response, retrieving, by a transceiver on the computing machine , the file from the remote machine and storing the retrieved file in the second isolation environment; (f) responding, by the filter driver , to the first request with the retrieved file; (g) intercepting, by the filter driver , a second request to access the file made by a second application executing in a third isolation environment; (h) redirecting, by the filter driver , the second request to the second isolation environment, responsive to the determination that the file is identified in the enumeration and that the second isolation environment contains the retrieved file; and (i) providing, by the second isolation environment, the second application with access to the retrieved file. <EOS>