Hey, Piston! Thanks for your review!
I was unaware of the error so I wouldn't be able to tell the cause, but I'm glad it's working now.
I also wish it would be possible to do what you said, but unfortunately Firefox doesn't offer that possibility. You either have to keep confirming each download or disable the option entirely. I think it would be a great idea to file (or find) a bug on Bugzilla for that.