I can't see all the code but...
1. don't use proc_kill just ent_remove(me); break;
2. debris = my hasn't to be in a loop
3. check if in cometa function is cometa = me;

I'm not sure that I'm getting your point but...
Code:

---

 
entity* player; entity* cometa; entity* debris;

function player_event
{
	if(event_type == event_entity)
	{
		if(you == landpad){Crash_detect.string="LANDPAD";}
		if(you == debris){Crash_detect.string="ASTEROID"; you.pan += 180;}
		if(you == cometa){Crash_detect.string="COMET"; ent_remove(you);}
	}
	if(event_type == null)
	{
		Crash_detect.visible = off;
	}
}

action player
{
	player = me;
	my.enable_entity = on;
	my.event = player_event;
}

action cometa_action
{
	cometa = me;
	my.enable_entity = on;
	my.pan= random(360);
	my.tilt= random(360);
	c_setminmax(me); 
	while(me)
	{
		c_move(me,vector(1,0,0),nullvector,GLIDE | ACTIVATE_TRIGGER | IGNORE_SPRITES | IGNORE_PASSENTS | use_box);
	wait(1);
	}
}

action debris_action
{
	debris = me;
	my.enable_entity = on;
	my.pan= random(360);
	my.tilt= random(360);
	c_setminmax(me); 
	while(me)
	{
		c_move(me,vector(1,0,0),nullvector,GLIDE | ACTIVATE_TRIGGER | IGNORE_SPRITES | IGNORE_PASSENTS | use_box);
	wait(1);
	}
}

---