Hi. I solved this problem with the removal tool of McAfee (find it in Google with "How to uninstall or reinstall supported McAfee products using the Customer Products Removal Tools" -I can't paste the link-). My problem was a bad uninstallation of a product of McAfee that installed "script proxy" that locked all local pages with scripts (Office logon, Google Drive logon, BTSync UI...). I know a bad uninstallation of Avast Antivirus can generate the same problem. Use their own removal tool to completely uninstall it. Good luck.
