Old Avant Browser user agent causes sites to redirect to mobile versions in IE

Avant Browser (an Internet Explorer shell) can come back to haunt you. When uninstalling, it leaves behind its addition to the Internet Explorer User-agent (in this case "Avant Browser [avantbrowser.com]"). That addition causes some sites to redirect to the mobile versions in Internet Explorer 8. In some cases, it is impossible to view the normal version of the websites because even deep links redirect to the mobile homepage. To fix the problem, remove the User-agent addition. You can search for "Avant" in regedit.