Crash reproduced on Windows XP with Inkscape 0.91.
Different crash (reproduced on Windows XP and Xubuntu 16.04) with lp:inkscape/0.92.x rev. 15155 when ungrouping (grouping doesn't crash, but shows unexpected results, as explained in the previous comments).
Crash reproduced on Windows XP with Inkscape 0.91.
Different crash (reproduced on Windows XP and Xubuntu 16.04) with lp:inkscape/0.92.x rev. 15155 when ungrouping (grouping doesn't crash, but shows unexpected results, as explained in the previous comments).
Crash not reproduced at all with Inkscape 0.48.5.