Content-Disposition IE bug

ok i know this has popped up a couple of times before but i'm still having problems. What I need is the download popup to popup and ask the user if they wish to save or open the file they want to download. If you click open IE saves the file in your temp cache and then opens up the associated proggy and for some bizare reason adds "[1]" at the end of the filename and cant find the file in cache. At the moment i'm using the following: Header("Content-Type: application/octet-stream"); Header("Content-Transfer-Encoding: binary"); Header("File-Length: $fileSize"); Header("Content-Disposition: attachment; filename=$filename"); Header("Content-Description: File from DMS"); fpassthru($fh);