Those are just download managers. They don't affect anything until I actually attempt to download with them. I've had them for a long time too and this is a recent development. I might have solved it though. Instead of removing Dreamweaver, I removed something called Macromedia Extension Manager... and it hasn't happened since. I'm going to give it more time before I officially say it's fixed though.
Edit: Sure enough, soon as I open my mouth it happens again. Sigh, time to uninstall Dreamweaver.
Edit #2: I kept using my browser as it was uninstalling. The problem persisted, and soon as it was done, instead of prompting me to download something, it took me to the source of the page. So it was definetly Dreamweaver. Hopefully restarting Firefox will solve this problem. If nothing strange happens, I'll reinstall Dreamweaver tomorrow and see if I can work around this.