I was having problems opening piece of software I need for work, which until a recent update of MS Silverlight worked really well on Firefox. I uninstalled Silverlight and re-installed an newly updated version - without any joy. So, I went to my Finder >> Applications Folder and dragged Firefox into my 'Trash'. So, now with no Firefox and no Silverlight I downloaded (via Chrome) 27.0.1 for Mac and installed it in the usual way, by dragging the fox into the folder presented by the .dmg fle downloaded (or directly into Application - I have done both, several times on this occasion). Usually, I can then eject the dmg file and the application works normally. But not so this time. The dmg file stays resolutely on the desktop and if I eject it, the next time I open Firefox, the .dmg file reappears and I have to go through the fox >> folder process again. I've tried deleting both again (although I cannot delete the dmg file - only eject) and then clearing the 'Trash' - but still .... it reappears. I'm now frustrated by all this and need to understand why this is happening. David