Are you getting pop-up ads when you access the website medianewtab.com? Medianewtab.com is an adware that will attempt to commandeer your browser search and homepage. The adware will send you to malicious websites to get money from you or infect your computer further. It may also prevent you from changing your settings back.
The adware brought about by medianewtab.com is usually installed through bundled software without you knowing. It has to be removed immediately.