I installed Windows 8.1 on my laptop, followed by an Ubuntu setup. The problem is that grup didn't seem to successfully set up itself on /sda. On the next bootup, Win8 started automatically, which is not what I want.
The solution was to boot up on the ubuntu live dvd and put these in the terminal:
sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install boot-repair
You just need to choose "Recommended repair" and follow the on-screen instructions.
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