Backtrace of the crash:

Program terminated with signal 6, Aborted.
#0  0xb775c424 in __kernel_vsyscall ()
(gdb) bt
#0  0xb775c424 in __kernel_vsyscall ()
#1  0xb6f7d5f6 in kill () from /lib/libc.so.6
#2  0x08111542 in fatal_error_signal (sig=6) at emacs.c:3900
#3  <signal handler called>
#4  0xb775c424 in __kernel_vsyscall ()
#5  0xb6f7d322 in raise () from /lib/libc.so.6
#6  0xb6f7eb0c in abort () from /lib/libc.so.6
#7  0x081145de in really_abort () at emacs.c:4796
#8  0x08111648 in assert_failed (file=0x83aca04 "indent.c", line=626, 
expr=0x83acb36 "elt >= 0") at emacs.c:4093
#9  0x081fdbe1 in vmotion_1 (w=0xb8fc220, orig=152, vtarget=151, 
ret_vpos=0xbfd22590, ret_vpix=0x0) at indent.c:626
#10 0x081fe065 in vertical_motion_1 (lines=303, window=193970720, 
pixels=0) at indent.c:730
#11 0x081fe140 in Fvertical_motion (lines=303, window=193970720, 
pixels=170016392) at indent.c:770
#12 0x0811ddcc in Ffuncall (nargs=3, args=0xbfd226e4) at eval.c:4165
#13 0x080b73f1 in execute_optimized_program (
    program=0xaffe064 
"\r\254\005\306\v!\025\f\254\005\307\v!\024\v\254\003p\023\r\fU\253\003ȇ
\212\214\311\n!\031ʎ
\313\n\v\"\210\vq\210~\210\r\f^\b\254\023\314\r\f]\256\002`SfU\253\a\r\f
]S\252\004\r\f]}\210eb\210\315\316 \n\"T,\207\t", <incomplete sequence 
\360>, program_length=84, 
    stack_depth=4, constants_data=0xa32126c) at bytecode.c:933
#14 0x0811c657 in funcall_compiled_function (fun=171897264, nargs=4, 
args=0xbfd22950) at eval.c:3746
#15 0x0811d627 in Feval (form=195284040) at eval.c:3972
#16 0x0811d552 in Feval (form=195283920) at eval.c:3962
#17 0x081178a2 in Fprogn (args=195283908) at eval.c:1024
#18 0x08117567 in Fif (args=195284412) at eval.c:933
#19 0x0811cde6 in Feval (form=195283872) at eval.c:3882
#20 0x0811d552 in Feval (form=195283788) at eval.c:3962
#21 0x0811815d in Flet (args=195283620) at eval.c:1181
#22 0x0811cde6 in Feval (form=195293988) at eval.c:3882
#23 0x0811d552 in Feval (form=195293904) at eval.c:3962
#24 0x081178a2 in Fprogn (args=196597248) at eval.c:1024
#25 0x080ff629 in Fsave_current_buffer (args=196597248) at editfns.c:408
#26 0x0811cde6 in Feval (form=196597260) at eval.c:3882
#27 0x0811d744 in Feval (form=195293856) at eval.c:3996
#28 0x0811d552 in Feval (form=195293772) at eval.c:3962
#29 0x081178a2 in Fprogn (args=195293760) at eval.c:1024
#30 0x081177f5 in Fcond (args=195269088) at eval.c:999
#31 0x0811cde6 in Feval (form=195293664) at eval.c:3882
#32 0x0811d552 in Feval (form=195293544) at eval.c:3962
#33 0x081178a2 in Fprogn (args=195293532) at eval.c:1024
#34 0x0811ed3f in funcall_lambda (fun=195293292, nargs=0, 
args=0xbfd23f68) at eval.c:4535
#35 0x0811e1ef in Ffuncall (nargs=1, args=0xbfd23f64) at eval.c:4224
#36 0x080b73f1 in execute_optimized_program (
    program=0xa9be6a4 
"\b\254i\016\032\306\\\016\033\307\\\016#\f\016\034\f\256\003\016$\016%\
016\035\016\036\v\310\311!\310\312!ˉ
\036&\030\036'\036(\036)\036*\036+\036\034\034\036,\036-
\036.\036\033\036\032̎\016/\255\002\v\315Ή
\211\211\036\n\036\t\036\036\036\035\036\060\033\016\037\256\006\016\061
\256\002\n\022\316\026\037\317\r\016\062\t#.\025\207\r\320N\211\036\063@
\036 \r\321N\036\021\r\322N\036\022\323\016 
!\036\064\r\016!B\036!\324\016\"B\036\"\r\325N\253\020\326\022\r\325N\32
7a\253\a\330\r\325\316#\210\016\065\253\006\331\t!\252\003\t .\a\207", 
program_length=178, 
    stack_depth=15, constants_data=0xad56ee8) at bytecode.c:933
#37 0x0811c657 in funcall_compiled_function (fun=194120224, nargs=3, 
args=0xbfd242d8) at eval.c:3746
#38 0x0811e14b in Ffuncall (nargs=4, args=0xbfd242d4) at eval.c:4214
#39 0x080b73f1 in execute_optimized_program (
    program=0xa9be6a4 
"\b\254i\016\032\306\\\016\033\307\\\016#\f\016\034\f\256\003\016$\016%\
016\035\016\036\v\310\311!\310\312!ˉ
\036&\030\036'\036(\036)\036*\036+\036\034\034\036,\036-
\036.\036\033\036\032̎\016/\255\002\v\315Ή
\211\211\036\n\036\t\036\036\036\035\036\060\033\016\037\256\006\016\061
\256\002\n\022\316\026\037\317\r\016\062\t#.\025\207\r\320N\211\036\063@
\036 \r\321N\036\021\r\322N\036\022\323\016 
!\036\064\r\016!B\036!\324\016\"B\036\"\r\325N\253\020\326\022\r\325N\32
7a\253\a\330\r\325\316#\210\016\065\253\006\331\t!\252\003\t .\a\207", 
program_length=178, 
    stack_depth=15, constants_data=0xad56ee8) at bytecode.c:933
#40 0x0811c657 in funcall_compiled_function (fun=194120224, nargs=3, 
args=0xbfd24560) at eval.c:3746
#41 0x0811d627 in Feval (form=195325876) at eval.c:3972
#42 0x081178a2 in Fprogn (args=195271356) at eval.c:1024
#43 0x0811ed3f in funcall_lambda (fun=195324940, nargs=1, 
args=0xbfd247b0) at eval.c:4535
#44 0x0811d96d in Feval (form=188745420) at eval.c:4023
#45 0x0811dd7e in Ffuncall (nargs=2, args=0xbfd24a60) at eval.c:4165
#46 0x080b73f1 in execute_optimized_program (
    program=0x9f0d4b8 
"\n\242\303a\253#\nG\304V\253\035\305\t\262\306\307\nAB!\263\022\b\253\r
\310\311!\210\312\313!\210\310\314!\210\n\207\n\242\315a\253\070\nG\304V
\253\062\316\nA@!\253+\317\n\320\"\256\002\321\nA@\306\304\n8!\"\210\305
\t\262\306\n!\263\022\b\253\r\310\322!\210\312\313!\210\310\314!\210\n\2
07\305\t\262\306\n!\263\207", program_length=109, stack_depth=6, 
constants_data=0xa31ea34) at bytecode.c:933
#47 0x0811c657 in funcall_compiled_function (fun=171973488, nargs=1, 
args=0xbfd24dac) at eval.c:3746
#48 0x0811e14b in Ffuncall (nargs=2, args=0xbfd24da8) at eval.c:4214
#49 0x080b73f1 in execute_optimized_program (
    program=0xac65368 
"\n\253\004p\252\002\306`\307\035\033\031\310\311\312 \030ˎ
\314\016\027!\210\212\307f\315a\256\006`Sf\315a\025\316\317!\210\r\253\n
\307f\320a\253\004\307u\210\214e\v}\210\321p!\211\034\242\322a\253\f\323
\324\325\f\326BBBD\252\002\f-!!+\207", program_length=85, 
    stack_depth=8, constants_data=0xa329a30) at bytecode.c:933
#50 0x0811c657 in funcall_compiled_function (fun=171968096, nargs=1, 
args=0xbfd25104) at eval.c:3746
#51 0x0811e14b in Ffuncall (nargs=2, args=0xbfd25100) at eval.c:4214
#52 0x080c3db7 in Fcall_interactively (function=169951048, 
record_flag=170016392, keys=170016392) at callint.c:973
#53 0x0811b8b6 in Fcommand_execute (cmd=169951048, 
record_flag=170016392, keys=170016392) at eval.c:3369
#54 0x0813c25b in execute_command_event (command_builder=0xa804ec8, 
event=180264808) at event-stream.c:4269
#55 0x0813cc98 in Fdispatch_event (event=180264808) at event-
stream.c:4605
#56 0x080cff6e in Fcommand_loop_1 () at cmdloop.c:623
#57 0x080cfd3c in command_loop_1 (unused_dummy=170016392) at 
cmdloop.c:528
#58 0x081199d2 in condition_case_1 (handlers=170015312, bfun=0x80cfd0b 
<command_loop_1>, barg=170016392, hfun=0x80cf91d <cmd_error>, 
    harg=170016392) at eval.c:2176
#59 0x080cfa35 in command_loop_3 () at cmdloop.c:285
#60 0x080cfa57 in command_loop_2 (unused_dummy=170016392) at 
cmdloop.c:298
#61 0x08119337 in internal_catch (tag=169750936, func=0x80cfa4c 
<command_loop_2>, arg=170016392, threw=0x0, thrown_tag=0x0, 
    backtrace_before_throw=0x0) at eval.c:1756
#62 0x080cfb6c in initial_command_loop (load_me=170016392) at 
cmdloop.c:336
#63 0x081102fa in xemacs_21_5_b33_i686_pc_linux (argc=1, 
argv=0xbfd25814, unused_envp=0x0, restart=0) at emacs.c:2742
#64 0x08110b45 in main (argc=1, argv=0xbfd25814, unused_envp=0xbfd2581c) 
at emacs.c:3190
(gdb)