There are no errors listed in the server error log.
Filesize doesn't seem to matter, I get the same message whenever it's a 2k file or a 20+meg file.
File extensions are set in the options (it's a .zip file).
Server settings show the max file size is 128M.
I'm stuck, any help would be great, thanks!
For reference on the error message, it's the same as posted in this thread: http://xenforo.com/community/threads/cant-upload-a-pdf.25578/