Calculations creating a javacript error message multiple times

When you divide by zero it returns Infinity.  Before a value is entered the empty field is zero.  When any field value changes, all calculations run.  When Infinity is the value of a field that is formatted as number, the formatting error will occur.  You can avoid this by using a custom calculation division script that first tests the divisor field for a value and only runs the equation if it has a value.  Otherwise return an empty string.  Here's an example for your "ters" field.  Instead of the simplified notation listtake/ers, enter the following custom calculation script:

var oFld=this.getField("ers").value;

if(!oFld)

{event.value=""}

else

{event.value=this.getField("lisstake").value/oFld}