Hi, You just need to click open menu on right most side of screen where you will found option button with wheel type image,Click on that Now in opened panel , go to to security and click on exception key at right must corner (The 1st one). paste the link or web address (found in address bar) from which you are disturbed.Click on allow. It will now block that site automatically. but there is no way to block all address with a domain (Ex .ru) YOU HAVE TO BLOCK SITES 1 BY 1. THANKS

Thank you, but doesn´t that do the complete opposite of what I need? It allows the pasted sites to install addons...

Then you need to get help from your Internet security programme like quick-heal because in those apps there should an option, you can block sites from there. for more help , please mail me with name of your computer's internet security name. Thanks.

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
• Anti-Rootkit Utility - TDSSKiller
• AdwCleaner (for more info, see this alternate AdwCleaner download page)
• 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!

Adblock Plus {web link} Blocks annoying video ads on YouTube, Facebook ads, banners and much more. Adblock Plus blocks all annoying ads, and supports websites by not blocking unobtrusive ads by default (configurable).

BlockSite {web link} BlockSite is an extension, which automagically blocks websites of your choice. Additionally, this extension will disable all hyperlinks to these websites, by just displaying the link text without the clicking functionality.

. Whenever you get a message / popup that software / files need to be updated;

DO NOT USE ANY OF THE PROVIDED LINKS

While this may be a legitimate message, it could also be Malware or a Virus. Any time you want or need to check for upgrades, go to the web site of the True Owner of the program in question. For example, to check out Firefox, go to Mozilla.org. {web link}

You can sent a report to The FBI via their web site Internet Crime Complaint Center (IC3) {web link}

You can also report such a site at; Google Report Phishing Page {web link} which is the same when done while on site by going to Help > Report Web Forgery

Help us safeguard Mozilla’s trademarks by reporting misuse {web link}

Thank you!!

The BlockSite does block .ru and all other unwanted sites so far :). 

But the empty tabs that pops up stays on the screen ... - I guess people are working on that problem. I read that I´m not the only one annoyed. The scanning for malware has still not resulted in any findings. Have a nice day!

Do a malware check with several malware scanning programs on the Windows computer. Please scan with all programs because each program detects different malware. All these programs have free versions.

Make sure that you update each program to get the latest version of their databases before doing a scan.

• Malwarebytes' Anti-Malware:
  http://www.malwarebytes.org/mbam.php
• AdwCleaner:
  http://www.bleepingcomputer.com/download/adwcleaner/
  http://www.softpedia.com/get/Antivirus/Removal-Tools/AdwCleaner.shtml
• SuperAntispyware:
  http://www.superantispyware.com/
• Microsoft Safety Scanner:
  http://www.microsoft.com/security/scanner/en-us/default.aspx
• Windows Defender:
  http://windows.microsoft.com/en-us/windows/using-defender
• Spybot Search & Destroy:
  http://www.safer-networking.org/en/index.html
• Kasperky Free Security Scan:
  http://www.kaspersky.com/security-scan

You can also do a check for a rootkit infection with TDSSKiller.

• Anti-rootkit utility TDSSKiller:
  http://support.kaspersky.com/5350?el=88446

See also:

• "Spyware on Windows": http://kb.mozillazine.org/Popups_not_blocked
• https://support.mozilla.org/kb/troubleshoot-firefox-issues-caused-malware