Recovering grub boot-loader after installing Windows

Installing Windows after Ubuntu will wipe out the boot-loader. To recover the boot-loader, follow the instructions here:
https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows

This worked great for me, except once. After doing the steps in that website, it directly booted into Ubuntu without listing Windows. Then I typed the following command, and it worked:

$ sudo update-grub