Main task titles partially overlap Month/Year labels when printing gantts

When I print a gantt chart, the titles of the main task groups show along the top in blue text in blue boxes, which is fine. Unfortunately, the month/year labels also show along this grey title area and the two overlap so that you only see the top half of the month/year text poking out above the pale blue task label box. Am I doing something wrong when I print - any ideas for rectifying please?
I’m running GanttProject 2.8.9 Pilsen (build 2335) on Windows XP Professional SP3