Here's the story:

I've upgraded from 12.04 (running alongside a Windows 7) to 14.04 from a DVD. I told it to delete the previous version completely, so it was technicaly a fresh install rather than an upgrade.

Everything seemed to work fine after the installation, so I played around a little and broke my desktop with some odd Compiz settings. I had no idea how to fix it quickly, so I decided to simply install Ubuntu again (and again deleting the previous version completely).

The installation ran through fine, but when it came to the reboot after the last step, I landed on a GRUB console:

                    GNU GRUB version 2.02~beta2-9



Minimal BASH-like line editing is supported. For the first word, TAB 

lists possible command completions. Anywhere else TAB lists possible 

device or file completions



grub> _

Oh well... After asking Google I assumed that this means that the bootloader doesn't know what to load.

So I entered the boot device selection on startup and saw this:

If I select "Internal HDD" in the Boot Manager, everything works fine - I get the purple GRUB screen and it even shows me my Windows 7. But having to call the boot manager on each start is not quite a solution.

So, wondering where the 2 Ubuntu entries came from, I took a look at the boot menu in the BIOS and found this:

So as far as I understand it has something to do with GRUB and UEFI, but I don't know enough about any of it to put it all together...

So my question is:
What's wrong here and how can I fix this?

When I shut down Ubuntu, it hangs on the purple screen, with the dots blinking, but even after 10 minutes nothing happens, so I have to switch it off. Rebooting works as expected, though.

Does it have something to do with the problem above?