There is no such thing as McAfee Search so not sure what that's about, possibly a SiteAdvisor message? As this appears to be caused by McAfee software as you've posted here, try uninstalling the software and running the MCPR cleanup tool (see Useful Links at the top of this page), reboot, & then try re-establishing the Internet connection (usually easily done by repairing the conection in Windows) then try reinstalling your software from the online account.
This may have been caused by a bad update that surfaced sometime yesterday, see the Announcement at the top here: https://community.mcafee.com/community/home
Hint: If you can't get he connection up and running straight away or can't download MCPR try downloading it to a removable flash drive - USB stick or similar.
I won't comment on the connection issues. As for the search-engine prompt : it may be something to do with SiteAdvisor. The SA options has a setting which says "Make Yahoo my browser's default search engine" and there's also a box you can check to enable Secure Search in the browser.
If it happens again perhaps halton could post a screenshot of this change-search-engine message.
Thank you for everything.