It may be that your down-trace is intermittantly failing. Try this.
c_trace(vector(my.x,my.y,my.z+50),vector(my.x,my.y,(my.z - 500)),IGNORE_ME|IGNORE_PASSABLE|IGNORE_SPRITES|USE_BOX);



"There is no fate but what WE make." - CEO Cyberdyne Systems Corp.
A8.30.5 Commercial