Here is the full backtrace :
GNU gdb 6.1-debian
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-linux"...Using host libthread_db library "/lib/tls/libthread_db.so.1".

Core was generated by `imap'.
Program terminated with signal 11, Segmentation fault.

warning: current_sos: Can't read pathname for load map: Erreur d'entrée/sortie

Reading symbols from /lib/tls/libdl.so.2...done.
Loaded symbols for /lib/tls/libdl.so.2
Reading symbols from /lib/tls/libc.so.6...done.
Loaded symbols for /lib/tls/libc.so.6
Reading symbols from /lib/ld-linux.so.2...done.
Loaded symbols for /lib/ld-linux.so.2
#0  mail_index_sync_init_expunge_handlers (ctx=0xbffff8b0) at mail-index-sync-ext.c:36
36      mail-index-sync-ext.c: Aucun fichier ou répertoire de ce type.
        in mail-index-sync-ext.c
(gdb) bt full
#0  mail_index_sync_init_expunge_handlers (ctx=0xbffff8b0) at mail-index-sync-ext.c:36
        handlers = (const mail_index_expunge_handler_t * const *) 0x80cae68
        extensions = (const struct mail_index_ext *) 0x6738
        id_map = (const uint32_t *) 0x1
        eh = {handler = 0, context = 0x0, record_offset = 0}
        handlers_count = 1
        id_map_size = 1860
        size = 3082539416
        idx_ext_id = 3082539384
        map_ext_id = 0
#1  0x080831ec in sync_expunge (e=0xb7bbd178, ctx=0xbffff8b0) at mail-index-sync-update.c:113
        view = (struct mail_index_view *) 0x80caac8
        map = (struct mail_index_map *) 0x80cd5b0
        count = 3082539384
        seq = 3082539384
        seq1 = 1862
        seq2 = 1862
        expunge_handlers = (struct mail_index_expunge_handler *) 0xb7bbd178
        i = 0
        expunge_handlers_count = 3082539376
#2  0x08083a90 in mail_index_sync_record (ctx=0xbffff8b0, hdr=0x80cd4f4, data=0xb7bbd178)
    at mail-index-sync-update.c:400
        rec = (const struct mail_transaction_expunge *) 0xb7bbd178
        end = (const struct mail_transaction_expunge *) 0xb7bbd198
        ret = 0
#3  0x08083f47 in mail_index_sync_update_index (sync_ctx=0x0, sync_only_external=1)
    at mail-index-sync-update.c:628
        index = (struct mail_index *) 0x80c6e68
        view = (struct mail_index_view *) 0x80caac8
        map = (struct mail_index_map *) 0xf148
        sync_map_ctx = {view = 0x80caac8, cur_ext_id = 4294967295, expunge_handlers = 0x80d3da0,
  extra_context_buf = 0x0, extra_context = 0x0, type = MAIL_INDEX_SYNC_HANDLER_INDEX,
  sync_handlers_initialized = 0, expunge_handlers_set = 0, expunge_handlers_used = 0,
  cur_ext_ignore = 0}
        thdr = (const struct mail_transaction_header *) 0x80cd4f4
        data = (const void *) 0xb7bbd178
        old_lock_id = 61768
        seq = 135033704
        i = 0
        first_append_uid = 0
        offset = 4430000952
        ret = 1
        skipped = 0
        check_ext_offsets = 0
#4  0x080824e8 in mail_index_sync_commit_external (ctx=0x80caa80, seq=0, offset=61864)
    at mail-index-sync.c:287
        ret = 0
#5  0x080826af in mail_index_sync_begin (index=0x80c6e68, ctx_r=0x0, view_r=0x0, log_file_seq=0,
    log_file_offset=18446744073709551615, sync_recent=0, sync_dirty=0) at mail-index-sync.c:367
        ctx = (struct mail_index_sync_ctx *) 0x80caa80
        seq = 1
        offset = 61864
        lock_id = 8
        seen_external = 135042384
#6  0x08062f1f in maildir_sync_index_begin (ibox=0x80c9550) at maildir-sync.c:579
        sync_ctx = (struct maildir_index_sync_context *) 0x80caa30
#7  0x08063616 in maildir_sync_context (ctx=0x80b2240, forced=0) at maildir-sync.c:912
        ret = 0
        new_changed = 1
        cur_changed = 1
#8  0x080637cb in maildir_storage_sync_init (box=0x80c9550, flags=0) at maildir-sync.c:975
        ctx = (struct maildir_sync_context *) 0x80b2240
        ret = 0
#9  0x0808b876 in mailbox_sync_init (box=0x0, flags=0) at mail-storage.c:329
No locals.
#10 0x0805e97d in imap_sync_nonselected (box=0x0, flags=0) at imap-sync.c:153
        ctx = (struct mailbox_sync_context *) 0x80c9550
        sync_rec = {seq1 = 134986640, seq2 = 134987528, type = 7}
        status = {messages = 1102598494, recent = 513357221, unseen = 131740, uidvalidity = 0,
  uidnext = 134984600, first_unseen_seq = 134987528, diskspace_full = 0, keywords_count = 134987528,
  keywords = 0x7}
#11 0x08057943 in get_mailbox_status (client=0x80bbc68, storage=0x0,
    mailbox=0x80c9550 "¨\226\f\b\220»\v\b \203\a\b@\203\a\b", items=0, status=0x0) at cmd-status.c:68
        box = (struct mailbox *) 0x80c9550
        failed = 1
#12 0x08057a7b in cmd_status (client=0x80bbc68) at cmd-status.c:110
        args = (struct imap_arg *) 0x80bbe58
        status = {messages = 135003808, recent = 134895249, unseen = 434, uidvalidity = 22,
  uidnext = 134987168, first_unseen_seq = 134982184, diskspace_full = 0, keywords_count = 134582362,
  keywords = 0x80bfea0}
        items = 23
        storage = (struct mail_storage *) 0x80bbb90
        mailbox = 0x80bbf08 "Crans.All-bureau"
        str = (string_t *) 0x80bbb90
#13 0x08058b75 in client_handle_input (client=0x80bbc68) at client.c:324
No locals.
#14 0x08058c48 in _client_input (context=0x80bbc68) at client.c:368
        client = (struct client *) 0x80bbc68
#15 0x0809d2d8 in io_loop_handler_run (ioloop=0x80ba9e8) at ioloop-poll.c:184
        data = (struct ioloop_handler_data *) 0x80baa10
        pollfd = (struct pollfd *) 0x80baa28
        tv = {tv_sec = 0, tv_usec = 801471}
        io = (struct io *) 0x80bbda0
        t_id = 2
        msecs = 0
        ret = 0
        call = 1
#16 0x0809c858 in io_loop_run (ioloop=0x80ba9e8) at ioloop.c:218
No locals.
#17 0x080605f9 in main (argc=1, argv=0x0, envp=0x0) at main.c:224
No locals.
