Thank you for your response. Looks like I was too stupid to have a look at the appdata folder. The logfile says:
2013-05-26 15:43:07 D:\good\-M- - Destroy.mp3, decoder: Windows Media Format (WMF) - CDecoderWMF::Open:95 failed [-1]
2013-05-26 15:43:07 D:\good\-M- - Destroy.mp3, decoder: Microsoft Media Foundation (MMF) - System error [126]: The specified module could not be found.
2013-05-26 15:43:07 D:\good\-M- - Destroy.mp3, decoder: Microsoft Media Foundation (MMF) - CDecoderMMF::Init:74 failed [false]
2013-05-26 15:43:07 D:\good\-M- - Destroy.mp3, decoder: Microsoft Media Foundation (MMF) - System error [126]: The specified module could not be found.
2013-05-26 15:43:07 D:\good\-M- - Destroy.mp3, decoder: Microsoft Media Foundation (MMF) - CDecoderMMF::Open:455 failed [-4]
I then came to my mind that I am using Windows 7 N (EU-Version without Windows Media Player). After downloading und installing newest WMP everything is working flawlessly! Cool.
greetings
Quimby