Nokia :: 6600 Slide Album Track Order?

I've recently got my hands on a Nokia 6600 Slide, and I'm quite happy with it. I would also like to use it as my personal music player, but I have one issue.When I listen to music, I mostly listen to the whole albums, and in the case of most albums I listen to, the track order matters a lot. However, when I copy an album from my hard disk to the memory card of my phone, I cannot get the album to play in the correct track order.

For instance, I click "Play" on an album I select in the Music Player application. Then, rather than playing tracks 1, 2, 3, 4, 5, 6 and so on, it plays track 4, 3, 6, 2, 7, 1, and so on - this track order is always the same (for one album at least), and it seems I cannot correct it. The "shuffle" function is turned off, mind you. The files are usually named "number. title.mp4", or "artist - number - title.mp4", and they all have track tags.