Hello FentoCy,
And welcome to Apple Discussions!
It sounds like a permissions problem is occuring somewhere.
Navigate to your iTunes Music folder that will probably reside in your "My Music" folder of *My Documents*, right->click on the folder and choose "Properties. From there, you should see a separate window pop up. Make sure the folder is set to both Read and Write and then tick the box that will apply it to all subfolders as well. Also, head to the
Security tab and make sure that your user account is allowed access. See if that helps.
For more help on setting permissions and such with Windows XP, check out this document.
http://support.microsoft.com/kb/308419
Hope this helps.
B-rock