Hi,
With Firefox (or Safari) you need to have the Java Runtime Environment installed on your Mac to use the Auctiva Uploader.
http://www.java.comDanno
Edit: I looked at your most recent listing and do spot something strange. In tracking your 3 photos on listing 170292528934 to their original stored image (the _o.jpg), they are stored at 16x16. That would explain why they won't supersize, but how they got to that size is a problem. I'd open a Support Ticket with Auctiva for investigation. Do they appear in your Images library at that size?