Sync Problem: Randomly resyncing tracks

[MSG]

Reciently when syncing an album (11 tracks) to my 32GB X Series (using MediaMonkey 3.2.4.1304 Gold Edition) I noticed 53 tracks were in fact synced.

After syncing I checked my Walkman, the extra tracks (which were previously on my Walkman) now had unknown Grenres and the album art was missing.

As a test I reconnected the Walkman and another 30 odd tracks were resynced, again grenres was unknown and album art was missing.

Anyone have any idea what is happening?