I've mainly seen it using the search function although sometimes it seems something else is going on (another process or something) that causes a skip. Generally though it results from pressing a button or remote button.
I'm sure you use the search function right Tony? Do a title search and as quick as you can on the remote press 7 3 3 2 2 (should get you close to Red Barchetta

) and see what happens.
It could be that the fact you only have 2000 odd songs makes the search not show this problem.