Symptom:
SGSN running build 15.0 (52963) hang for 30 seconds and many sessmgr crashes occurred with the same signature causing all subscribers to be disconnected. 

********************* CRASH #03 ***********************
SW Version          : 15.0(52963)
Similar Crash Count : 29
Time of First Crash : 2014-Jan-16+14:11:51

Assertion failure at snutil/sn_memblock.c:188
  Function: sn_memblock_cache_get_mcblock_by_addr_slow()
  Expression: mcblock
  Proclet: sessmgr (f=87000,i=7)
  Process: card=5 cpu=0 arch=X pid=6362 cpu=~10% argv0=sessmgr
  Crash time: 2014-Jan-16+13:12:14 UTC
  Recent errno: 11 Resource temporarily unavailable
  Stack (3032@0xffffd000):
    [f7e285a1/X] libc.so.6/kill() sp=0xffffd268
    [0a9d1c33/X] sn_assert() sp=0xffffd298
    [0a9cc0e4/X] sn_memblock_cache_get_mcblock_by_addr_slow() sp=0xffffd2d8
    [0a9cc2d9/X] sn_memblock_cache_free() sp=0xffffd308
    [06698f61/X] sessmgr_gprs_sgsn_context_suspend_rsp() sp=0xffffd4a8
    [067df64d/X] sn_gt_handle_suspend_time_out() sp=0xffffd508
    [051b261a/X] tlib_serv() sp=0xffffd548
    [051b233b/X] tlib_tmr_tick() sp=0xffffd578
    [046937df/X] snx_timer_service() sp=0xffffd598
    [0469217f/X] snx_fast_service() sp=0xffffd5c8
    [05c6b494/X] sessmgr_snx_tick_callback() sp=0xffffd5f8
    [0aa61a46/X] sn_loop_run() sp=0xffffdb88
    [0a84b6f4/X] main() sp=0xffffdbc8

Conditions:
This happened after modifying a command by adding network-sharing common-plmn mcc 238 mnc 66

The command that was modified/added in under gprs-service gprs:

       plmn id mcc 238 mnc 02 network-sharing common-plmn mcc 238 mnc 66