I cannot post even a medium sized image to facebook.com (and other sites) using Firefox (12). I can post a 16KB image file to facebook.com (and other sites) successfully using Firefox, Safari, and Chrome. Why is Firefox failing to successfully upload even medium sized images? [https://img.skitch.com/20120506-b23y9s3wit93nr9rn9w4ycxu84.jpg Picture of Firefox failing to upload a 6.2MB image to facebook.com] [https://img.skitch.com/20120506-d9i634bu1ia4up9h8cbe5ag4kr.jpg Picture of Firefox failing to upload 6.2MB image to my server (with error detail)] [https://img.skitch.com/20120506-b1ns56atbfh3xi2nr28eexuneq.jpg This shows that Safari is successful where Firefox fails with 6.2MB image upload] [https://img.skitch.com/20120506-b7xqq2d8p26bd1uyax8s5qqnnb.jpg This shows that Firefox IS successful when uploading a very small image (16KB)]