You may have ad/mal-ware. Further information can be found in this article; https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-caused-malware?cache=no

Run most or all of the listed malware scanners. Each works differently. If one program misses something, another may pick it up.

Your system details show that you didn't have the latest version of uBlock Origin when you posted this - have you installed the latest version yet  ?

https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/

In addition to what FredMcD suggested, would you also do this please :

Go to the 3-bar menu => Addons => Extensions and look for any unfamiliar or suspicious looking extensions, like e.g.:

SafeSearch Incognito SearchAssist Incognito

When you find any :   remove them.

Also look in : 3-bar menu (or 'Tools') => Options => Advanced => Network tab => Under : 'Offline Web Content and User Data'

Do the same in Windows' Control Panel => Programs.

However :   most malware will be 'hiding' somewhere , hence the malware scans, as suggested by FredMcD.