I just installed Ubuntu 13.10 alongside windows 7. Because I could only boot Windows 7 I started Ubuntu live again from the DVD and ran boot repair.
Now the Computer is not able to boot anything. The error message "Please install an operating system on your hard disk" occurs.
I'm not even able to get into the 'normal' BIOS anymore: first time it worked and I could have changed the boot-options, but I left without changing anything. Now, when I want to enter the BIOS, only System Diagnostics appears with four options to chose from.