My grandmother was using her PC when she clicked on a popup window stating she had a virus and offering help. Well, after calling the number and allowing someone to access her computer, they told her she had some problems and they could fix it for $200 and get a 5 year waranty. She installed some software per their direction.
I heard about this a week later and I was very suspicious of this activity so I did a reset of windows - allowing it to wipe all personal files.
At this point I want to ensure there aren't any trojans or rootkits installed.
Please provide guidance on how to proceed.
Thank you in advance,