1. Click on the Firefox button in the upper-left of your browser and click on Options — it’ll pull out a little submenu when you hover over it with your mouse, but you can ignore that and just click right on the word Options. 2. Select the Content tab and make sure that “Block pop-up windows” is checked. If it isn’t, check it.

It sounds like a problem with the mimeTypes.rdf file. This tells Firefox what to do with what type of file.

Type about:support in the address bar and press enter.

Under the page logo on the left side, you will see Application Basics. Under this find Profile Folder. To its right press the button Show Folder. This will open your file browser to the current Firefox profile. Now Close Firefox.

Locate the mimeTypes.rdf file. Then rename or delete it. Restart Firefox.

@Antarakhedkar: Didn't solve anything. You're thinking of pop up ads. This is firefox pop up homepage.

@FredMcD: Didn't work either. The only thing it did was slow down the frequency of how often it does it.

Hmm, it's a start. How often do those windows come up? What was the site doing at the time?

It popped up about 15-25 windows every hour. When I did what you said, it slowed it down to 5-10 an hour. It would slow down the whole computer while it pops up. Whenever firefox pops up, it'll only show my homepage. If I want to go on another site, it will redirect back to my homepage. I can only use another site if I open firefox/Chrome manually. Even if I'm offline, it will still do it. Same issue with Chrome.

Is this a Flash-based or Java-based game you're playing in the browser? I got confused by this part:

Even if I'm offline, it will still do it.

If your default browser starts opening mysteriously, this can indicate that external malware is sending URLs to Windows to launch in your default browser. This doesn't match that pattern very well because real pages aren't opening. Still, if you haven't scanned recently, please try the cleaning tools in our support article: Troubleshoot Firefox issues caused by malware. Those are free and take considerable time to run. If they finish quickly and request payment for cleaning, you should try the forums in that article for advanced assistance.

Agreed.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

@jscher2000: What I mean is when I disconnected myself from the internet. The games I play include Age of Empires/Mythology and NDS games on the emulator.

chinky_candie said

The games I play include Age of Empires/Mythology and NDS games on the emulator.

These are all Nintendo games that run on an emulator? I don't imagine the original games would be randomly seeking network access, but what about the emulator itself: does it need anything from the outside world that it might be requesting in a particularly dysfunctional way? Does it work any better with Internet Explorer set as the default browser?

I haven't had IE installed. I only have Firefox and Chrome.

So I used Malware Bytes to scan my computer. There were infected files, but its still popping up. But only once an hour now. Usually when I'm not using the internet it'll pop up.

Getting there though.

Are you opening the page from within Firefox or as an external application e.g. in Windows Explorer?

^ Neither. Its doing it on its own.

@ jscher2000: So the once every hour pop up happens during the day. Its more frequent during the evening.

You may have ad / mal-ware. Further information can be found in the Troubleshoot Firefox issues caused by malware article.

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Downloaded all malware programs. No help. Issue still persisting.

Does it make a difference what browser you set as the default browser?

No. Chrome does the same thing.

Its getting worse.

Is this a fair summary after the last exchange:

Q: Does it make a difference what browser you set as the default browser? A: No. Chrome does the same thing.

The unwanted windows:

• open when you are running NES games in the emulator, which is a separate program outside of your browsers

• open in the currently set default browser --
  • regardless of which browser you are currently using
  • even if all browsers were closed
  • even if the network is disconnected (computer is offline)

It sure sounds like your emulator wants something from the network OR wants you to see something from the network (like an ad). Does the program have any tech support to help sort this out?

I've had this emulator since 2012. But the pop ups have been happening for the past 2 weeks. I haven't been downloading anything in that time. Since every time I do want to download, I get far too annoyed with the popups. Just yesterday in one hour, I had 87 pop ups which froze my computer :(

Maybe run some more of the malware cleaners in case Malwarebytes Anti-Malware didn't get everything. This definitely sounds like something outside of your browsers that you need to hunt down and kill.