Try eject the disk image by selecting it in a Finder window and pressing the command+E keys or by using the Finder's File menu.

If you find that the Firefox disk image will not eject, it is probably because of a Leopard bug, that prevents disk ejection, after you've copied files from one drive to another. Ejecting the disk via the Disk Utility should still work.

see here for more info and photos:

https://support.mozilla.com/en-US/kb/Installing%20Firefox%20on%20Mac

thank you

Please mark "Solved" the answer that really solve the problem, to help others with a similar problem.

Thanks, but nope---didn't work. I just went to Finder, located and highlighted the Firefox 8.0.1.dmg file, and when I go back to Finder's File menu the "Eject" option isn't black (i.e. it's gray and unresponsive to clicks). Also, I didn't copy any files from one drive to another. I have only one drive on this computer, a 3.4 ghz i7, with 8gb of ram. And you're talking about Leopard. Am I to assume that OS X 10.6.8 is synonymous with "Leopard?" Thanks for your help.

go from file menu then eject firefox, you must have dmg file in desktop, try one more:

https://support.mozilla.com/en-US/kb/Installing%20Firefox%20on%20Mac

thanks again

Okay--actually I just tried going through disk utility. It says "Eject failed. The disk 'Firefox 8.0.1.dmg' could not be unmounted. Marke sure that all applications and files are closed on this disk." What confuses me is that we keep talking about this thing like it's a disk. It's not. It's just a 30mb downloaded file. Also, it shows the FF orange disk-drive icon as a "subset" of the FF8.0.1.dmg file. Does that mean anything?

Thanks for the link. I have already read that page. The problem isn't getting the orange disk-drive icon to go away. I can eject that. The issue is that then when I reopen FF it asks me that same stinking question again regarding the disk image. Thanks.

Besides----I can't eject the orange FF diskdrive icon without also having to shut down firefox. Please keep in mind that I don't have problems closing and opening the program. I just don't understand what this disk image question is all about and why 1) it keeps asking it; 2) Why I can't "eject" it by seemingly any means. Thanks for being patient.

On OS X, a large majority of applications that you download will be in .dmg format. .dmg stands for “disk image” and it basically functions like a hard drive. DMG files can be mounted and ejected just like a regular hard drive. The purpose of the .dmg file is for compression. It can greatly reduce the size of the file you are downloading.

After you’ve moved the application file to your Applications folder you then eject the “drive” the DMG created from your desktop to the trash can in the dock. This does not delete the DMG file, it just un-mounts it. Since you have installed the application, you no longer need the DMG file. Drag the DMG file to the trash to delete the DMG file itself.

I almost thought we had success---but alas, no. I did go up to Apps and drag the dmg file down to the trash. I then reopened FF and got the same message: "Firefox" is an application downloaded from the Internet. Are you sure you want to open it? "Firefox" is on the disk image "Firefox 8.0.1.dmg." Firefox downloaded this disk image today at 10:11 AM. " Then I can choose to open, cancel, or show disk image. It also has a box I can check that says "Don't warn me when opening applications on this disk image."

Yes, I realize that this will keep the window from popping up, but it still doesn't address this whole disk image thing.

Do anyway I get to thinking that maybe that memo popped up because I hadn't emptied the trash. So with FF still shut down I try to empty the trash. Nope. It gives me this message: 'The operation can't be completed because the item "Firefox 8.0.1.dmg" is in use I can then click stop, or continue.'

Keep in mind this is with FF closed, with the orange diskdrive icon ejected, and everything snuggly put away in the Apps folder (except for the dmg file which is sitting in the trash being a pain in the neck).

Can't Empty the Trash

If you're having trouble emptying the Trash, start by holding down the mouse on the Trash icon itself. When you choose Empty Trash from the pop-up menu, Mac OS X empties the Trash without complaint, locked files and all.

If emptying the Trash gives you "Could not be completed because this item is owned by ...," you're trying to move or delete another Mac account holder's stuff. As you know, that's a big no in Mac OS X.

In that case, just make yourself the new owner of the file or folder

Nope---didn't work. I've owned Macs for about 12 years so although I am brain dead on some things, I do have a working knowledge on most things. I only say that to say this--I did try holding down the mouse and choosing empty trash. It asks if I want to permanently delete what's in there. I say yes--and then I get the same identical message again-----'The operation can't be completed because the item "Firefox 8.0.1.dmg" is in use I can then click stop, or continue.' So apparently that complains the same way it does if I click it up on the menu :)))

As for item owned by---that's not an issue and isn't coming up. User is not a problem either as I am the only user on this system. There is only ONE file in my trash at the moment at that is this dmg file. Nothing Mac. Nothing owned by anyone other than Firefox. The problem seems to be that the dmg file and the original 4.0 FF file are working in tandem with each other--even though I have already drug the new 8.0 globe into the Apps folder and it updated the FF app with the new stuff. If I could force the dmg file to go away, I would do so, but at every turn the system is telling me it can't be done because it seems to think that dmg file is in use---even though everything is shut down and/or ejected. Hey--I'm getting ready to head out and won't be back till evening. I'll check back in this evening. Thank you again for your help.

if you like another option to empty trash use the terminal command:

sudo rm -rf ~/.Trash/*

but make sure you have not in there something needful

thanks again

ideato, Thank you for the terminal command info. Dude--that was the one piece of advice you gave that brought me past my point of knowledge. I opened a help window and typed in "terminal command" and even my help window didn't have any suggestions. Sorry, but I don't know what/where/how a terminal command is. So I guess I'm just going to snuff the symptom and live with the problem sight-unseen. By that I mean that I'll go ahead and leave the dmg file in my apps folder (actually it doesn't matter where it is because my computer refuses to delete it no matter where it is), and simply click the box on the warning message to quit telling me about it. It will always haunt me as to why I have to be so ignorant on these things---but after awhile--out of sight will be out of mind. Such is the philosophy of an upper-middle ager who on some days is bummed at fogged memory--and on other days counts it a blessing :)) Thanks for helping me run all the options. I will check back one last time tomorrow just in case you decide to tell me how to do terminal commands. However, if you don't write I will appreciate no-less! Blessings. Thanks again.