It has to do with the Apple HFS+ driver. Solution here:
http://support.apple.com/kb/HT3841 or cached here:
http://209.85.129.132/search?q=cach...l=de&ct=clnk&lr=lang_en|lang_de&client=safari
http://support.apple.com/kb/HT3841 or cached here:
http://209.85.129.132/search?q=cach...l=de&ct=clnk&lr=lang_en|lang_de&client=safari