The File Input Goes Blank When Trying To Submit Form?

I have one document that resides in an iFrame, and it contains anywhere from 1 to 4 forms, depending. There is a dynamic content area that will display between zero and three forms, each named uniquely, associated with files that exist in a database. Regardless of the number of forms associated with a file, at the bottom of the document is one last form named NewDoc - this last form is used for uploading a new file into the database, or replacing a file.With one exception, this is working flawlessly.The user is supposed to choose a file for upload, use a SELECT input to say what document type it is, then click on the submit button.

What is actually happening, however, has me confuzzed. When the submit button is clicked the first time, the value of the input="file" element becomes blank and nothing happens. If a file is chosen, again, and the submit button clicked, it uploads with no problem and the database does what it's supposed to. But if I refresh the document and try, again, same thing - the file disappears from the form element and the form does not submit.First, the forms (all three, just in case):

Code:
<form name="updateDocs_1" id="updateDocs_1" method="post" style="margin:0px; padding:0px; border:0px;"
action="supplier_docs.cfm?vid=122" enctype="multipart/form-data">

[code]....