Hello BastianW. I would like to assist you if you need it. Please provide the exact issue and the following information:
1. The computer model number. If you require assistance locating this information, please reference this website: http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&docname=c00033108
2. Your operating system. If you require assistance locating this information, please reference this website: http://windows.microsoft.com/en-CA/windows/which-operating-system
3. Have you installed any new hardware on this computer, before the issue appeared?
4. Have you installed any new software or drivers on this computer, before the issue appeared?
Please respond as soon as possible. I look forward to your response.
Mario