hello, this may be an issue with adware on your system, so please perform all these steps:

1. refresh firefox (this will keep your bookmarks and passwords)
2. afterwards go to the firefox menu ≡ > addons > extensions and in case there are still extensions listed there, disable them.
3. finally run a full scan of your system with different security tools like the free version of malwarebytes and adwcleaner to make sure that adware isn't present in other places of your system as well.

Troubleshoot Firefox issues caused by malware

Good Morning,

I live in Poland and for some time I have a problem with my web browser Mozilla Firefox. When enabled, you can sometimes gives me an error message or with a browser can not download a newer version of Firefox. From there a long time when I leave my computer and I do not use it for sure about the time and have enabled browser that sometimes pop up I do not need advertising, even on the entire page with unnecessary things without my knowledge so it's done. When I open a new tab does not turn me to a new screen, Google only other junk browsers that attach themselves and do not want to let go. Yet I noticed that the browser is not me smoothly, or has opuznienia also has a known bug: no response . It's getting to automatically. I would like you to do something about it because I really like the browser, and a very long time I use it, and I do not want this because of specially of installing Google chrome. My English is not perfect for any errors sorry.

Regards Alice fine