So I just removed the DVD-drive from the machine and installed Win 8.1 from a USB-stick. What I noticed now (also on previous installation attempts), when windows boots the first time it says there is no battery connected (battery symbol in the tray). After a few minutes of working with the new installed windows I hear that sound (something connects e.g. USB-device or when you install a new GPU driver) and the display turns black again. The sound appears a second time and the display stays black. I tried to hit some keys and it responded with some sounds. After a few keystrokes it rebooted and showed me the bs again. Maybe it is installing some drivers via the internet which are corrupted?! Im starting wondering if it is the GPU driver. I checked for an BIOS update but it is up to date and a reinstallation is not possible.