Iceseyes, thanks for your hint [1] at ubuntuforum: it solved my problem :)
[1] http://ubuntuforums.org/showthread.php?t=394299&highlight=black+windows+compiz
Iceseyes, thanks for your hint [1] at ubuntuforum: it solved my problem :)
[1] http:// ubuntuforums. org/showthread. php?t=394299& highlight= black+windows+ compiz