While doing a download I've had my browser Hi Jacked by Yahoo and another lesser known e shield safe web.  I usually read the notices before accepting the download but I must have missed some thing.  I did a search and found Yahoo is well known for creating this problem.  Microsoft provided a malware scanner and a way to set the Microsoft webpage at IE start.  I also used windows defender.
Both the windows defender and the malware scanner reported no problems.  When IE was started it went to Microsoft which I was able to change to Google. 
Carl2