Translation from german text above:

Can't download songs with Xolox, it stucks at 00%! Am I doing something wrong?

Answer: Just wait longer. It happens often that your opponent is busy, and even sometimes you never get it. In the search window try to select files with a higher score (= number of hosts whitch offer the requested file).

Here is a grafic animation that shows the princip of gnutella:
http://www.limewire.com/gnutella_flash.html