I have two gp2x's. The game freezes on startup on one of them (running 1.4.0) and works okay on the other one (running 1.2.1). It's the same SD card. On the one where it freezes, this is what comes out of the serial port:
Datadir: /mnt/sd/supertux-0.1.3-bin/./data
ac97_codec: AC97 Audio codec, id: WML18 (Wolfson WM9711/9712)
ac97_codec: AC97 Audio codec, id: WML18 (Wolfson WM9711/9712)
ac97_codec: AC97 Audio codec, id: WML18 (Wolfson WM9711/9712)
screen width: 320, height: 240
and then nothing more. black screen.
On the machine where it works, this is the output on the serial port:
Datadir: /mnt/sd/supertux-0.1.3-bin/./data
screen width: 320, height: 240
SDL_SYS_JoystickInit
Don't know if this helps any.