Progress "Fence" on each Startup- Windows XP

[chee]

OS spec: win xp sp2

recently at each startup after shutting down the pc by the "shut down" option, there's a fence of bars ( like the one appears at booting-up after hibernating a pc), indicating the booting up progress

how come this bothers? progress bars appears at booting up after hibernation, but not after a norm "shut down"

any ideas?

Thanks