update to firefox 23 and check for malware.

See

• Update Firefox to the latest release

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.

I´ve found this: http://urlquery.net/report.php?id=4824828 this may help

Try Firefox Safe Mode to see if the problem goes away. Safe Mode is a troubleshooting mode, which disables most add-ons.

(If you're not using it, switch to the Default theme.)

• Open the Help menu and click on the Restart with Add-ons Disabled... menu item while Firefox is running.

Once you get the pop-up, just select "'Start in Safe Mode"

If the issue is not present in Firefox Safe Mode, your problem is probably caused by an extension, and you need to figure out which one. Please follow the Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems article for that.

To exit the Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.

Please report back soon.

thanks computerWhiz. I did what you said. And the problem dissapeared. Working In safe mode the pop-ups (are those "pop-ups"?) dissapeared. So I will have to try and find witch add-on it´s the one with the "undesired present". I wonder what can I do with that add-on then, because I need it. ¿suggestions?

An alternative it was given to me: to use an application called adwCleaner. The sistem seems clean on the last 3 hours. I don´t know if I can give a link to the anti-malware forum where I found it. (or may be I wait a couple of days untill I´m absolutely sure It worked).

I wait for your answers. Thanks a lot.

If you could post the name of the add-on causing the issue, then I can try to help you find an alternative.

It is not a good idea to download third party add-ons. You should only download add-ons from the Mozilla Add-on Store.

Sorry for the delay. I cannot report what add-on was the one that caused that trouble. As I said, I used a programme called adwCleaner and it was a success. Not a problem since then, so I couldn´t figure out witch was the problematic one.

Thanks ComputerWhiz.