Hi,
Are you sure you are using the latest code from the source code repository?
There was a bug fixed recently in the FileDialog page where it was losing the client id param after uploading a file it would redirect and lose the parameter. It required closing the dialog and re-opening it to select the file after uploading. I noticed it when I integrated the new jPlayer media player contributed by Kerry Doan and I fixed it.
Hope that helps,
Joe