Taskbar tabs are missing on Windows Vista

Hi,
I just encountered a problem with one of my computer programs. It says, I need to use the task manager for me to end its process. However, to my surprise, I do not seem to see all the tabs that were previously in there. I know there were six of them. I know there should be Applications, Processes, Services and the likes, but I do not see them.
I tried rebooting my Vista computer, just so the system will be refreshed, but it did not work. When I pull up the task manager, same thing appears. All my task manager’s tabs are gone! How do I get it back?
Help!
