[CentOS] Problem with gnome

Hi all,

I am using Centos 4.1 with Gnome and my updates are OK (When I do yum 
update, I have nothing anymore)

Normally, with GNOME there's a task bar in the bottom of the screen. If 
we open an application and we minimize its window, it is always 
avalaible in this task bar. There are other things in this task bar : a 
button on the left which is used to minimize all the opened windows and 
4 buttons on the right which are used to change the workspace.

Yesterday, I had a problem with the station and I had to shut it down 
with the power button of the Linux station. After a restart, I had a 
message telling me that there were three applications which were shutted 
down uncleanly (I don't remember which) and know  there is nothing 
anymore in the taskbar at the bottom of the screen (it is gray). The 
error message doesn't appear anymore.

Does anybody already had this problem ? What can I do to restart this 
taskbar ?

Thank you for your help.

Jean LEE