Why does system's 'time' changes while reboot ?

Issue

• System's time changed while rebooting.

Mar  5 08:43:26 xxxxx smartd[4302]: smartd is exiting (exit status 0)
Mar  5 08:45:33 xxxxx xinetd[2729]: Exiting...
Mar  5 08:45:40 xxxxx ntpd[2745]: ntpd exiting on signal 15
Mar  5 08:45:50 xxxxx auditd[2333]: The audit daemon is exiting.
Mar  5 08:45:51 xxxxx pcscd: pcscdaemon.c:572:signal_trap() Preparing for suicide
Mar  5 08:45:51 xxxxx pcscd: hotplug_libusb.c:376:HPRescanUsbBus() Hotplug stopped
Mar  5 08:45:52 xxxxx pcscd: readerfactory.c:1379:RFCleanupReaders() entering cleaning function
Mar  5 08:45:52 xxxxx pcscd: pcscdaemon.c:532:at_exit() cleaning /var/run
Mar  5 08:45:52 xxxxx kernel: Kernel logging (proc) stopped.
Mar  5 08:45:52 xxxxx kernel: Kernel log daemon terminating.
Mar  5 08:45:53 xxxxx exiting on signal 15
Sep  4 15:29:05 xxxxx syslogd 1.4.1: restart.
Sep  4 15:29:05 xxxxx kernel: klogd 1.4.1, log source = /proc/kmsg started.
Sep  4 15:29:05 xxxxx kernel: Linux version 2.6.18-308.8.1.el5 (sandman@localhost) (gcc version 4.1.2 20080704 (Novell 4.1.2-52)) #1 SMP Wed May 30
 02:50:38 EDT 2012
Sep  4 15:29:05 xxxxx kernel: Command line: ro root=/dev/rootvg/rootVol00 quiet rhgb quiet
Sep  4 15:29:05 xxxxx kernel: BIOS-provided physical RAM map: