Not sure if this is the best forum category for this question but hopefully a programmer might know;
I use Mas OSX 6.8
Problem: On Firefox, a pop up advert slides up from the bottom of screen on random pages I go to on the net. And, some times a page will redirect to an advert or somewhere else like an answers page.
Is this a virus? or has some kind of plugin installed itself or something else?
I did use Clamxav on my whole computers files but no recent virus was detected.
How can I get rid of this?