this is a iis problem see below
To resolve this problem, verify that the file requested in the browser's URL exists on the IIS computer and that it is in the correct location.
Use the IIS Microsoft Management Console (MMC) snap-in to determine where the file requested must exist in the IIS computer's file system.
This is particularly important if the Web site uses a virtual directory (VDIR). A VDIR is a directory that is not contained in the home directory of the Web site, but appears to client browser as though it does. This virtual directory must be mapped to a subfolder on a drive or reference the files by name.
For example, assume that the URL that caused the 404 error is http://Microsoft.Com/Test/File1.htm
, and the IIS snap-in shows that for Microsoft.Com Web site, the /Test/ directory is actually a virtual directory that maps to the location of c:\Information on the IIS computer. This means that you must verify that the File1.htm file is located in the c:\Information directory (and that the file name is spelled correctly).
IIS6 Dynamic Content: A 404.2 entry in the W3C Extended Log file is recorded when a Web Extension is not enabled. Use the IIS Microsoft Management Console (MMC) snap-in to enable the appropriate Web extension. Default Web Extensions include: ASP, ASP.net, Server-Side Includes, WebDAV publishing, FrontPage Server Extensions, Common Gateway Interface (CGI). Custom extensions must be added and explicitly enabled. See the IIS 6.0 Help File for more information.
IIS6 Static Content: A 404.3 entry in the W3C Extended Log file is recorded when an extension is not mapped to a known extention in the MIME Map property. Use the IIS Microsoft Management Console (MMC) snap-in to configure the appropriate extension in the MIME Map. See the IIS 6.0 Help file for more information.
to get roung it zip up files before uploading them then get user to unzip after download