It is only too easy with the best intentions to download something nasty.
Only yesterday I was sent some text to be poshed up for an advert in our village magazine.
I don't know what software was used, (the garage is better at cars than it is with computers), but the file had a subscript of .aww
Windows couldn't find anything to open this weird file, but Google search led me to Speedyfix While trying to install, this brought a rash of objections from the Firewall. I persisted briefly and was soon convinced that this Speedyfix was Malware. I couldn't stop whatever was trying to take over.
So perhaps I overreacted, but with a disobedient computer, I shut down and rebooted from the CD to restore a recent copy of (C:)Acronis.
All's well again, the only overhead was 40 mins restoring and CClean-ing then updating Windows with the Wednesday security lump.