Hi all, probably a dumb question. But I have an imac, and its my first time using any mac at all. I downloaded firefox, but its a little strange because 1) Firefox is showing up under devices, and it has an eject button next to it as if its a drive or something. 2) anytime I restart the computer, the firefox icon at the bottom is gone and replaced with a question mark. when I click it, the dialogue box pops up and says "firefox was downloaded from the internet, do you want to open it? etc.." but did I do something wrong when downloading it? I downloaded chrome too and these things aren't happening.