I'm having issues with a file uploading utility in my PHP application. When sending large files (9MB+) over the form, I get a very odd behaviour: the POST data I've included in the form dissapears, including the file information.

I've already increased all PHP limits I could (time limit, max input time, post max size, memory limit and upload max filesize) and I still can't get the proper behaviour. I've tried replacing the regular HTTP forms with a Flash-based solution (SWFUpload, www.swfupload.org), still the same behaviour.

I've tried multiple files of similar sizes and its definitely not a particular file issue. I've debugged the POST vars sent using Firebug, and the correct variables are still there in the header, together with the file.

What could be going on here?