Boot Repair never worked for me. Despite the dual boot, Windows booted every time and so I had a workaround using
Escape key and following up Boot Options from there which was always an inconvenience. Another temporary fix had to be repeated. So the permanent that has been successful is discussed ahead.
gksu gedit /etc/default/grub
In this file, find the line:
Edit this line to look like:
Save the file and issue a final command to flush the new changes:
sudo grub-mkconfig -o /boot/grub/grub.cfg
Reboot and enjoy!