All of a sudden I cannot upload images to my Photobucket account. There never has been a problem with it before... I can upload using Internet Explorer so what's happened to Firefox?
Does that uploader use a Flash object or Java applet ?
I believe it's -shockwave-flash
You can try to clear the Flash Local Storage.
Flash Website Storage Settings panel:
See also Flash Local storage settings
Try disabling the TACO Add-On; if that works then turn TACO off for Photo Bucket dot com. Worked for me.