I think I may have found my own answer.
I was creating the value in the two numeric fields by using:
protected double NUMERIC_VALUE = 0.00d;
then,
obj.setNumericfield( new BigDecimal( NUMERIC_VALUE ) );
When I changed the setter statement to:
obj.setNumericfield( new BigDecimal("0.00"));
it started working.
I didn't think that creating a BigDecimal with a double would cause a numeric overflow,
but it appears that was the issue.
BTW, we're using JDK 1.6, with JBoss 5.1.0.