This is very strange. When I upload a file with IE7, it does not put the file in the $_FILES array, rather it goes into the $_POST array as 'form_element_name' => 'filename.extension'. I have stripped out all javascript, other form fields, and everything else to no avail. I'm not doing anything like modifying the form element contents, and whether I create the form element with javascript (mootools) or just normal html, I get the same result. Immensely weird.
I'm using browserstack.com for the IE7 machine, if that might have any relevance. IE8+ and every other VM they offer work fine.
Anyone have any ideas or seen this before? Google turned up nada.