Pop-ups! They keep... Popping up!?

[Katelynn]

Okay, I'm very careful with my laptop... It's a Toshiba, runs Windows 7.

I only get on sites like Facebook, eBay, YouTube, Yahoo- the "safe" stuff... But lately I've been getting a bunch of pop-ups! I'm getting pop-ups that Avast says has viruses... I close them as soon as I see them, but there was a pop-up that I didn't notice... I ran a scan, but nothing was found.

How can I stop these? Sometimes the yellow/tan warning thing comes at the top of the browser, but not always! I've even seen porn pop-ups, but I don't visit porn sites- afraid of getting viruses/malware.

Any help?
I'm using FireFox

[António]

Disable the Web Antivirus.
I have Avast, but not on web surfing.
It warns me if i'm in risk tho

[Problem Solved]

If Avast! has detected the popups as viruses then there should be an option that allows you to find the source and terminate the virus. In other words there should be an option that says, Delete Viruses

[Sandy]

get and run malwarebytes run a quick scan you have adware and malware malwarebytes is very good and free get at filehippo.com>>>> after you malwarebytes and remove all it finds get ADBLOCK PLUS it will keep all those ads from coming back go to firefox add-ons its free good luck.

[DunbarPappy®ϟϟ]

Try "MalwareBytes" to start cleaning up your system:
http://www.malwarebytes.org/
(free version has no "real-time" shield)

The following mods help, but methods ("vectors") are dynamic, and users must be aware of emerging threats.
FIREFOX: Tools> Options> Privacy> top drop slot set to "Firefox will use custom settings..."> Check 'Accept Cookies from sites'
â–ºUn-Check 'Accept 3rd Party cookies'.

A good collection of effective security & privacy add-on's (Official Mozilla) is here:
https://addons.mozilla.org/collections/d...nbarpappy/
"AdBlock Plus" (with 'subscription' added) helps defray rubbish.
►► At minimum, get the #1 item for malware prevention: "NoScript", which constrains automagically fetching & deployment of potentially tainted assets, and offsets the Microsoft install if it's rubbish.
Bookmark and refer to this page for how it works, and how to use it when sites don't function as you need: http://noscript.net/features#contentblocking