script makes unity hang... pls help

i have a script that is attached to a plane and it is supposed to transform its position but … dosent show any errors… but stops the engine . Here is the script:

function Start () {

while (true){

if(Score.psy==1)
{
 transform.position = Vector3(0, 0, 1.5);
 yield WaitForSeconds (5);
 Score.psy=0;
 transform.position = Vector3(0, 0, -1.5);

}



}
}

There is no yield in your while loop

the while(true) is big give away, but you should try and put a yield return null, right after the brackets outside the if