If you use Glest under Linux (tested with Ubuntu Edgy, 6.10) if there's any problem in the XML files (units, buildings, etc.) the game crashes without any notice.
It should say why it crashed.
If you want you could even (for Windows and Linux) let it don't crash but: (a) say the problem and go back to start menu or (b) ask you if want to ignore the problem, skip the unit / building and continue.