scatter chart insists on plotting as a line chart
 

Excel 2003: had 2002 version. Data plotted correctly. Next time I opened
file, data displayed as a series rather than a scatter chart, though the data
range fields for x and y coordinates display the proper ranges. Tried
rearranging my data into adjacent columns, creating new charts and ranges,
upgrading to 2003 Excel, changing chart into other types and back again...am
I missing a primary concept?