A SEGFAULT happens with blender 2.43 on Ubuntu, when exiting the game engine a second time with ESC:
#0 0x00000004 in ?? ()
#1 0xb7ea98a2 in dict_dealloc (mp=0xb6ee90b4) at ../Objects/dictobject.c:766
#2 0xb7f01e3f in _PyImport_Fini () at ../Python/import.c:207
#3 0xb7f0c695 in Py_Finalize () at ../Python/pythonrun.c:378
#4 0x0857243b in BPY_end_python ()
at source/blender/python/BPY_interface.c:220
#5 0x082fd753 in start_game () at source/blender/src/space.c:528
#6 0x08428718 in do_view3d_buttons (event=152)
at source/blender/src/header_view3d.c:4589
#7 0x082c9267 in do_headerbuttons (event=152)
at source/blender/src/headerbuttons.c:2004
#8 0x082413a3 in scrarea_dispatch_header_events (sa=0x90017f0)
at source/blender/src/editscreen.c:530
#9 0x08242d1c in screen_dispatch_events ()
at source/blender/src/editscreen.c:1192
#10 0x08243714 in screenmain () at source/blender/src/editscreen.c:1459
#11 0x0822d5bc in main (argc=1, argv=0xbfc88b24)
at source/creator/creator.c:715