Portaldosites/Qvo6 is a browser hijacker. It modifies the browser's home page. It is distributed via re-packed freewares - take note the installation of Portaldosites/Qvo6 is often pre-checked.
Several solutions are possible:
Uninstall through the Control Panel
For Windows Vista/Seven/8: Go to the Control Panel, then Programs and Features (or Uninstall a program), look for Portaldosites/Qvo6 and uninstall. For Windows XP: Open the Control Panel, then Add / Remove Programs, look for Portaldosites/Qvo6 and uninstall. Then, go to your browser options and uninstall (if present) the Portaldosites / Qvo6 add-ons. Don't forget the change your homepage. If this persists, reset your browser like this: Reset your browser. Remove Portaldosites/Qvo6 shortcut for your browser. Right-click the shortcut and select "Properties." > "Shortcut", check if Portaldosites/Qvo6 is not present in the "Target".