killing stubborn processes

On occasion I've had a program freeze (mostly it's xine). I haven't been
able to kill the program when this happens.

I've tried restarting X, all that does is remove the applications
interface from my screen. `ps -ax` still shows it as running.

I've tried `kill` and that has no effect.

So my question is how do you kill a process when `kill` doesn't work?


Thx,
Bart