why i get the 404 page?

I opened a webpage and it jump to a site i dont want to visit.just found some words like 404.

Your problem I encountered, may be somr virus poisoning the beginning program, and later I checked my computer with antivirus software.the result let me suprise , there is no virus.And then i found the reason, some website can no visit temporary,then it will jumps to the website owner setting page which caused 404 error page.This situation will not cause any problems in the use of computers.otherwise, you can clear the temporary internet files on the internet options seeing whether the site is online.