Windows 2000 and Word 2000

I began a table with one row that has 3 columns.  To add
rows I simply highlight the entire row. Next I select
table, insert, rows below.  An identical row is added
below the row I highlighted.

I can look at the table properties and review the
preferred width of each column in my rows.

Somehow rows in my table have been added where the columns
appear to be different widths from my original row.  I do
not know how I added rows that appear to be different
widths.  The first two column widths seem to agree with my
original row but the third column is not as wide as my
original row.  The rows look different on the screen and
in printouts.    

Looks can be deceiving though.  Here is the strangest
part.  When I click table properties and review the
preferred width of each column the width of the short
column agrees with the width for that column in my
original row!  All the preferred widths in the short row
agree with the preferred widths in my original row.  Yet
on the screen and in printouts the row is obviously
shorter than the other rows above it.

Any ideas on how to fix this would be appreciated.