when i'm using multiple file uploads and leave some of the fields empty,
then i get
  sizeof($upload) > sizeof($upload_type);
(i assume that the problem is that $upload_type[] is not set to an empty string ""
 for files with $upload_size[$i] == 0)

so if i a have an upload form with 2 upload entries, and i leave the first one blank,
then sizeof($upload) == 2 and sizeof($upload_type) == 1 which means that
the type for  $upload[1] is in the variable $upload_type[0]