I wrote a application (Pure ASP Code) to upload the file from client PC to web server (NT 2000) . It works with no error, but when I open the uploaded files, the files are corrupt except the extension is "txt" (text file).
It also works other two web servers (NT 2000) but the uploaded files are not corrupted.
Why the files are corrupted??

Don't know but if you're wanting to try another solution here is a resource for letting the user upload a file which is something that was unfortunately not built into ASP:

ASP File Upload Using VBScript by John R. Lewis - 7/10/2000
http://www.aspzone.com/articles/john/aspUpload