hi friends , some times when i shut down the database
it hangs, and in alert log file it notes ' waiting for active calls...'

i restarted the system. i am sending the alert log file contents
and trace file also. can u plz tell what could be the reason
and in future will become problem??

IN alert log file:

Thu . Oct 19 17:56:12 2006

shutting down instance: further logon disabled
shutting down instance(immediate)
licence high water mark = 34

The Oct 19 18:01:19 2006

Active Call for Process 3685 user 'oracle' Program ' oracle@hp2(s000)
shutdown: waiting for active calls to complete

also the trace file :

Oracle9i Enterprise Edition Release - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release - Production
ORACLE_HOME = /opt/ora9/product/9.2
System name: Linux
Node name: hp2
Release: 2.4.21-32.ELsmp
Version: #1 SMP Fri Apr 15 21:17:59 EDT 2005
Machine: i686
Instance name: oracle
Redo thread mounted by this instance: 1
Oracle process number: 13
Unix process pid: 4834, image: oracle@hp2 (TNS V1-V3)
*** SESSION ID:(26.905) 2006-10-19 18:01:19.715
SHUTDOWN: waiting for active calls to complete.
*** 2006-10-19 18:06:25.715
SHUTDOWN: waiting for active calls to complete.
*** 2006-10-19 18:11:31.715
SHUTDOWN: waiting for active calls to complete.

my shell program to shutdown is :

sqlplus /nolog<< EOF
conn sys/sys as sysdba
shutdown immeditae
!lsnrctl stp