Uploading Files with PHP

Hi, I am trying to set a small script that would let my clients upload file with a Explorer or Netscape, but the problem is it would let me upload any file that is great than a 1MB. We get an error that the file "none" could not be read. I have set the upload_tmp_dir=/tempupload is has been chmod to 777, php.ini as been set to 20MB, I know that is a lot but we are engingeering company that work with CADD files. Any clues where to look? The PHP 4 Bible from IDG states that we have to under HTTP uploads, but nothing else. Is there some where on the net that explains better what I have to set up, turn on, or haven't done? Thanks, Chuck