I found the answer. Hope it you'll help someone in a near future : )
Here is the step by step approach:
a) Open your iTunes Mac
b) download the script by MrC, administrators of the forum:
https://dl.dropboxusercontent.com/u/87189402/itunesm3u_2_MC.zip c) export each playlists in iTunes m3u8 format on your desktop
d) drag each list in m3u8 format on the icon of the downloaded script
e) when all is done, drag the lists m3u8 format in a USB key
f) connect the USB key in a Windows computer and open iTunes
g) import playlists in Windows iTunes
h) When finished, export playlists in m3u8 format on the computer desktop
i) Finally, open Windows JRiver and import the iTunes Windows playlists m3u8 on the desktop and voilą!
I think the problem lies in the different Mac-Windows encoding Latin characters.