Fixed in Origin 2018. Bug introduced in Origin 2017 SR1. For Example:

1. Click New Graph button to open a graph window.
2. Double click x axis to open Axis dialog.
3. Go to Reference Lines tab.
4. Click on 3rd row.
5. Click Insert button.
6. Now the cursor is in in-place edit mode. With the in-place edit mode, click the Line checkbox of the 3rd row. ==> Origin crashes.