Thanks EvilSOB. I'm kinda new on script optimisting. I guess it makes it better. But still, I am getting the same crashes.
But this time, I tried to track it down wisely;
I started commenting the lines which I think are causing this and I found it.

When I commented the line
Code:
if (tcam!=NULL)
c_move(tcam,vector(offset.x,0,0),nullvector,IGNORE_MODELS);


All worked fine without crashing. And when I uncomment it, I ge t the crash again - but only when I press the '->' button on my keyboard.

my current code is this:

Code:

///////////////////////////////////////////////////////
// 			INCLUDES
///////////////////////////////////////////////////////

#include <acknex.h>
#include <default.c>

///////////////////////////////////////////////////////
// 			VARIABLES
///////////////////////////////////////////////////////

VECTOR offset;

ENTITY* cam;
ENTITY* actor;
ENTITY* tcam;

var attach;

//////////////////////////////////////////////////////
// 			   ACTIONS
//////////////////////////////////////////////////////

action camera_action(){
	cam = me;
	while (me!=NULL){
		wait(5);
		camera.x = cam.x;
		camera.y = cam.y;
		camera.z = cam.z;
		camera.pan = cam.pan;
		wait(5);
	}
}

action actor_action(){
	actor = me;
}


action tcam_action(){
	tcam = me;
	while (me!=NULL)	
	{	   
		if (actor!=NULL)
		{
		   my.x = actor.x;
		   my.y = actor.y;
		   my.z = actor.z;
		   my.pan = actor.pan;
		}
		
		wait(5);
   }
}


/////////////////////////////////////////////////////
// 			   FUNCTIONS
/////////////////////////////////////////////////////


function initCamOffset(ox,oy,oz){
	offset.x = ox;
	offset.y = oy;
	offset.z = oz;
	cam.x += offset.x;
	cam.y += offset.y;
	cam.z += offset.z;
	return vector(cam.x,cam.y,cam.z);
	wait(5);
}


function attachCam(){
	attach = true;
	wait(5);
}

function removeCam(){
	attach = false;
	wait(5);
}


function actorForward(){
	c_move(actor,vector(4 * time_step,0,0),nullvector,GLIDE);
	c_move(cam,vector(4 * time_step,0,0),nullvector,GLIDE);
	wait(5);
}

function actorBackwards(){
	c_move(actor,vector(-4 * time_step,0,0),nullvector,GLIDE);
	c_move(cam,vector(-4 * time_step,0,0),nullvector,GLIDE);
	wait(5);
}


////////////////////////////////////////////////////
// 			MAIN
////////////////////////////////////////////////////

function main(){
	
	// load level
	level_load("game.wmb");
	wait(5);
	
	// initialise the offset
	initCamOffset(30,0,15);
	
	// tcam set up
	attachCam();
	ent_create(NULL,nullvector,tcam_action);
	
	while (1){
		
		while (key_cuu){
			actorForward();			
			wait(1);
		}
		
		while (key_cud){
			actorBackwards();
			wait(1);
		}
		
		if (key_cur){
			attachCam();
			while (key_cur){
				actor.pan -= 8 * time_step;				
				//  trouble-maker line - the cause of the crash
				if (tcam!=NULL)
				   c_move(tcam,vector(offset.x,0,0),nullvector,IGNORE_MODELS);				
				cam.x = tcam.x;
				cam.y = tcam.y;
				cam.z = tcam.z;
				cam.pan = tcam.pan;				
				wait(5);
			}
			removeCam();
		}
		
		wait(1);
	}
	
}


I just can't see what is causing the crash.
Any help much appreciated ppl.