download error

ok i want to use a function so that users can download off me. i want it in asp so that i can restrict ppl from downloading. i have the function as follows:



if strFileType = "" then strFileType = "application/download"


Set fso = Server.CreateObject("Scripting.FileSystemObject")
Set f = fso.GetFile(strFilename)
intFilelength = f.size
Set f = Nothing
Set fso = Nothing

Response.AddHeader "Content-Disposition", "attachment; filename=" & strFile
Response.AddHeader "Content-Length", intFilelength
Response.Charset = "UTF-8"
Response.ContentType = strFileType

Set Stream = Server.CreateObject("ADODB.Stream")
Stream.Open
Stream.type = 1
Stream.LoadFromFile strFileName

Response.BinaryWrite Stream.Read
Response.Flush

Stream.Close
Set Stream = Nothing



somefiles work fine when downloading this way ,.,, but some won't download and i get an "Internal server error"

What is wrong :S?

Thanks
Kris