Hi Frechesmaedl, I'm so sorry we missed your post!
Can you kindly try uninstalling Little Musician completely (i.e., choose to remove all data during uninstall) and then redownload the Little Musician installer from your BrillKids Account. Do try if the newer version installs and works properly for you.
If you are still having problems, please write to us at support[at]brillkids[dot]com and include these details:
1. The exact error message you saw on screen (or a screenshot of it)
2. Your diagnostic report. For instructions on how to create a report, see:
http://support.brillkids.com/entries/20438423-How-to-Create-a-Diagnostic-Report-for-your-BrillKids-Learning-SystemI hope this helps!