After extensive tinkering and pasting the code from my script view into SQL editor and running there I have discovered it's not the two measures causing the problems. It's two date conversions which I had removed from the view output, however they were still in the SCRIPT box of the calculation view. When I pasted everything from script box into SQL editor I quickly realized that once I took these date conversions out the numeric overflow error disappeared.
Here are the problems;
TO_DATE(H.BUDAT, 'YYYYMMDD')
TO_DATE(M1.ERDAT, 'YYYYMMDD')
These were being converted to feed a microstrategy prompt in the report front end.
-Patrick