Is Malware Causing Endless Script Error Messages?

Hello.

Does anyone know if endless Script Error messages are caused by malware? I have run a few different virus scans and CCleaner. None of them found anything. On this site, the Script Error says "addthis is undefined."

Background: Upgraded to Win 10 last week. Tried Edge but didn't like it so switched back to Internet Explorer. When I go online, I get a Script Error message for most sites, and have to click either Yes/No or X several times to get rid of it. Often that doesn't help and I usually end up having to use End Task to close down the browser.

The links that appear often lead to ads. The most common is adadvisor, but once I click it away, other ad links appear such as adlegend.

Has anyone used freefixer to get rid of adadvisor http://www.freefixer.com/b/remove-adadvisor-net-from-firefox-chrome-and-internet-explorer/ and if so, does it also get rid of other ad links that result in a Script Error message?

I have IE (in “Advanced”) set to disable scripts on IE and everywhere else and to not repeat the Script Error message (sample pic attached; the links change each time and are always related to ad sites), but it still happens.

TIA

 

Thank you.