(gdb) bt
#0  0xffffe410 in __kernel_vsyscall ()
#1  0xb7d1edf0 in raise () from /lib/tls/i686/cmov/libc.so.6
#2  0xb7d20641 in abort () from /lib/tls/i686/cmov/libc.so.6
#3  0xb7d1843b in __assert_fail () from /lib/tls/i686/cmov/libc.so.6
#4  0x082d258a in ha_myisam::index_read (this=0x8b1de48, buf=0x8b538a8 '?' <repeats 117 times>, key=0x8b65568 "\001", key_len=18, find_flag=HA_READ_KEY_EXACT) at ha_myisam.cc:1534
#5  0x08234508 in safe_index_read (tab=0x8b651fc) at sql_select.cc:10901
#6  0x082345f7 in join_read_always_key_or_null (tab=0x8b651fc) at sql_select.cc:11348
#7  0x08235e6c in sub_select (join=0x8b63658, join_tab=0x8b651fc, end_of_records=false) at sql_select.cc:10584
#8  0x08235c9a in evaluate_join_record (join=0x8b63658, join_tab=0x8b65088, error=0, report_error=0x8b0358c "") at sql_select.cc:10701
#9  0x08235e83 in sub_select (join=0x8b63658, join_tab=0x8b65088, end_of_records=false) at sql_select.cc:10585
#10 0x0823f199 in do_select (join=0x8b63658, fields=0x8b643c0, table=0x0, procedure=0x0) at sql_select.cc:10348
#11 0x08253e94 in JOIN::exec (this=0x8b63658) at sql_select.cc:2088
#12 0x0824f8ee in mysql_select (thd=0x8b032c0, rref_pointer_array=0x8b04388, tables=0x8b55560, wild_num=0, fields=@0x8b042f8, conds=0x8b56988, og_num=0, order=0x0, group=0x0, having=0x0, proc_param=0x0, select_options=2156153344, 
    result=0x8b56aa0, unit=0x8b04034, select_lex=0x8b04264) at sql_select.cc:2266
#13 0x08254194 in handle_select (thd=0x8b032c0, lex=0x8b03fdc, result=0x8b56aa0, setup_tables_done_option=0) at sql_select.cc:255
#14 0x081e7486 in mysql_execute_command (thd=0x8b032c0) at sql_parse.cc:2674