Cannot boot to Ubuntu after Windows 7 installation and "boot-repair" does not work

I hope someone here can help me:
I re-installed my Windows 7 partition and now I cannot boot to Ubuntu 14.04 any more - no grub boot-menu is display instead directly the "Loading windows" screen is shown.

If I go to the boot menu in BIOS I can select my Ubuntu - drive and boot from it (which is quite cumbersome).

So I tried to use "boot-repair" as described at at the help pages but the program exits with an error.

This is the link I get from "boot-repair": http://paste.ubuntu.com/7558812/