url redirected to another site

When my daughter puts "www.yahoo.com" in, this is what comes up:"hey, it worked/The SSL/TLS-aware Apache webserver was successfully installed on the website...." This is a large improvement over what it was before - a sex site search engine. I have searched all files, deleted temp files, checked all of her internet options (using Firefox, but it comes up with IE as well). Any ideas?

 

Might be a browser hijacker: run the malware thread
http://forums.majorgeeks.com/showthread.php?t=35407

 

also might try this. Start run, cmd, then hit ok, ipconfig /flushdns

 

I would check her Host file also, if that got hijacked, someone could redirect a browser anywhere he wanted.