Since 2 or 3 days my keyboard is disabled when media is played. It doesn't matter if it is music or video, in a browser oder local media players (even when an advertisement started playing on this website while I was typing this text). As soon as something is playing, ALL keys of the keyboard stop working. After I close the media (close browser tab or media player), the keyboard works normally again.
For a long time I used a simple program called 3RVX that lets me adjust the sound volume with keyboard shortcuts (click here shortcuts of this program are the only thing that still works when playing media. Deinstalling it didn't solve my problem. Since 3RVX seems to be a small private project, I do not expect any support from the developer.
Except for this program, I don't have any clue what could wrong with my PC. I could not find anything on Google for this. Any help would be highly appreciated!
Windows 8.1 Pro 64-bit, newest updates installed