I think the problem is real player try unistall it or scann your PC, can be a malware

Sometimes a problem with Firefox may be a result of malware installed on your computer, that you may not be aware of.

You can try these free programs to scan for malware, which work with your existing antivirus software:

• Microsoft Safety Scanner
• MalwareBytes' Anti-Malware
• TDSSKiller - AntiRootkit Utility
• Hitman Pro
• ESET Online Scanner

Microsoft Security Essentials is a good permanent antivirus for Windows 7/Vista/XP if you don't already have one.

Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Did this fix your problems? Please report back to us!

I ran the MalwareBytes-anti-malware and the rootkit. I did a restore, I started Firefox in the safe mode, I uninstalled/reinstalled Realplayer. Nothing I have tried makes any difference. The file/download is in my documents folder. When I try to delete it a pop-up says it's unable to delete it because it's running in Firefox. It is not shown in my documents file if I open it while I'm using IE nor is it causing any problems in IE. It seems to only exist in Firefox. Now what?

Did you search the downloads history and possibly the normal history for references to this file or server?

Boot the computer in Windows Safe Mode with network support (press F8 on the boot screen) as a test to see if that makes it possible to delete this file.

I couldn't find the pop-up when I was in safe mode (F-8) but as soon as I go back to normal it appears. In the tool bar at the top that reads from left to right:' file-edit-view-history-bookmarks-tools-help' is where I find the file(?) under history. When I right click on it to see if I can delete it the black downlod arrow in the navigation bar shows an active download in progress even though I am no longer on the website and have tried to delete it numerous times. This is only in Firefox not IE (but I don't like or use IE)

See more information about download manager:

• Find and manage downloaded files

Hello

We can see the presence of user.js file in your Firefox profile, this file is not present or created by default so, please try deleting this file and also disable the RealPlayer Downloader plugin .

Please See:

How to fix preferences that won't save

http://kb.mozillazine.org/User.js_file#About_the_user.js_file

Disable or remove Add-ons

I couldn't find how to access that js file (I know nothing about PC's) so I reset Firefox. That seems to have solved my problem. Thanks for all the help! It is always appreciated.

                                                  lige

This is what fixed it for me. I went to the HISTORY tab.Then click "show all history". Then over towards the left side panel choose/click the "DOWNLOADS". That should show you what is (trying) to download or is an (active) download, (which is why you get that pop up when you try to shut down Firefox Browser). So now you have to click or highlight whatever is showing in the right hand download box and either click the X in the top right corner or whatever you have to click to get it to delete it as a download. Seems you first had to "pause" or "stop" the download, then you could DELETE it. Anyway, if that is the same thing that's happening for you , this should be an EASY fix without running all the spyware stuff or reloading software or rebooting in safe mode. Mine seemed to happen for some reason for just doing something I always do which was starting a web page to play a radio station. I must have accidentally hit something to start to try to download it while I was on the page listening. In my situation, there was not any progress being made by the bar that usually shows how much has been downloaded. It was just there showing as an active download with no progress. Hope that might be the answer for anyone reading this same problem. Good Luck all