Indeed, it's the same problem as in bug 454.

The savegames are from 0.14.1 and are corrupted in the same way as the ones from
bug 454. There are negative obstacle types at level 14:
  t-767 x52.50 y23.50
  t-767 x52.50 y32.50
  t-767 x3.50 y35.50

Daniel, in the attachment you can get a fixed savegame file. Copy it to your
.freedroid_rpg folder and the game should run fine.