Some devices only support synchronization to the device's root
directory (e.g. Sandisk Sansa devices).
If synchronization halts as soon it begins without copying any
tracks, try changing the destination format so that it doesn't
use any subdirectories:
e.g. <Artist>-<Title> instead of /Music/<Artist>-<Title>
Some devices support a limited number of files per directory.
If synchronization halts partway through, it is possible that
changing the destination format to use a subdirectory will solve
e.g. use /Music/<Artist>/<Album>-<Title> ...instead of /Music/<Artist>-<Title>