On MSWindowsXP: since I upgraded from 4.2.2 to 4.2.3 release all my table
borders are gone from all my documents.
NOTA BENE: on my OSX Mavericks 4.2.3 works correctly w.r.t. this subject.
Already reported (and fixed) as Bug 76195 - regression: with "Table Boundaries" disabled, the borders of tables are not visible.
*** This bug has been marked as a duplicate of bug 76195 ***