They are 2 Ipods, 4th gen, I use mine with OSX and my sister's one works on the PC. The problem happens on the PC, I thought it could be some configuration problem in the Ipod or Itunes. Ive reinstalled Itunes several times but the problem still is there.
Ive exported the library and saved as a xml file in the Itunes folder but when the problem happens again I cant open the .xml.