Sorry to be a pain on this but still having the same issue. Tried from two different Macs and a Window computer (yes I'm a geek as well as different pictures, using the Uploader and uploading straight from the My Gallery site. Maybe we need to delete my profile and start over? Error messages from Mac and Win follow.
First I started with NEF then converted to jpg, full resolution. For these shots, I know I needed to resize so (in PS) resaved in a smaller jpg size and also tried saving for web option. Not sure if this answers your question.