whenever i download something, and go to the download menu, and try to open the file, a message pops up and says that firefox cannot open the file because it has moved since you last downloaded it. Idk why it does that and rely need help... Thanks
Try to open it using Explorer or Finder (either you use Windows or Mac OS X) in the place you saved it. If the file is there, you're fine, there's only a extension fail on Firefox, that as I know reinstalling will solve the problem, if the file is not there, look you're internet connection or try reinstall firefox (it's saying you it's downloading but it's not, another fatal error). If not, try to save the same file using another browser (Safari, Chrome or Internet Explorer) and watch if the file goes on straight. If not, look your internet connection.