Success at last!!! The first link found that the ‘data executive prevention’ (whatever that is) was disabled. I still wasn’t able to search anything after that, so uninstalled IE 11 so that it went back to version 10. Everything seems to be in perfect working order now. THANK YOU!!! I can’t tell you what a relief that is. I’m one happy lady ;D

And apart from Avast, which of the scan tools I downloaded would be prudent to keep and use regularly?