I found if I used the plant tool ie plants in a line it would hang.
Then later I discovered that this would happen depending on which plant symbol I used.
These ones would hang:
symbol number 2, 15 or 25.
These ones were ok:
symbol number 5, 10 and 20.
We wondered if this was a hardware prob...but on a Mac we got the same results.
We also discovered that with the plants that hang, if we adjusted the spacing so there wasn't any (or little) overlap then it was ok.
we also found that the volume of planting also was a factor in making it hang. If we used plant symbol two and drew a short line of plants of say 10 plants or so it was ok. But if we covered our A4 sheet with lines it would hang.