While changing folder (cascade folder)

#0  0x408fe26b in free () from /lib/libc.so.6
#1  0x408fe0f3 in free () from /lib/libc.so.6
#2  0x407414eb in g_free () from /usr/lib/libglib-1.2.so.0
#3  0x807bfcd in remove_node_diff (ml=0x81e25d0, node=0x81ebd10, depth=0)
    at message-list.c:1503
#4  0x807c074 in build_subtree_diff (ml=0x81e25d0, parent=0x81ea510, 
    path=0x81ea540, c=0x81ea3a0, row=0xbffff908, expanded_nodes=0x81e4f00)
    at message-list.c:1536
#5  0x807bb62 in build_tree (ml=0x81e25d0, thread=0x81ea3e0)
    at message-list.c:1340
#6  0x807cf23 in cleanup_regenerate_messagelist (in_data=0x81ff1e8, 
    op_data=0x81ff230, ex=0x81ff220) at message-list.c:2102
#7  0x8077ac2 in cleanup_op (msg=0x818bba0) at mail-threads.c:796
#8  0x8077a4c in read_msg (source=0x810fc60, condition=G_IO_IN, userdata=0x0)
    at mail-threads.c:768
#9  0x4073ebf0 in g_io_add_watch () from /usr/lib/libglib-1.2.so.0
#10 0x407402b9 in g_get_current_time () from /usr/lib/libglib-1.2.so.0
#11 0x407408c3 in g_get_current_time () from /usr/lib/libglib-1.2.so.0
#12 0x40740a5c in g_main_run () from /usr/lib/libglib-1.2.so.0
#13 0x404e9457 in gtk_main () from /usr/lib/libgtk-1.2.so.0
#14 0x400ee099 in bonobo_main () at bonobo-main.c:270
#15 0x8079ec7 in main (argc=1, argv=0xbffffbc4) at main.c:100
#16 0x408aabdc in __libc_start_main () from /lib/libc.so.6