This is probably the last place someone with this problem will look, but I've just gone through Hell trying to install Microsoft Office 2016. I turns out that even when responding Yes to allow the install to make changes to the computer, Webroot prevents any changes to Excel's registry entries and doesn't inform you that it blocked the changes needed in the install. This prevents Excel being set up as an app associated with .xls and .xlsx file extensions so, while calling Excel directly, you can open spreadsheets and save new ones, but you cannot open those files directly and have Windows 10 recogise it is associated to Excel--you get an error saying there is no default program for that type of file. Six hours of Microsoft support (no exageration) later, reinstalling Office, repairing Windows, etc., etc. we finally disabled Webroot and voila, Excel can now be assigned as the app for these file types. It would be nice if Webroot informed you when it blocks a registry or associated app change from taking place. It even blocked changing the registry directly through regedit!. So what does "Allow xxx to make changes to your computer" Yes actually do?