taskbar: tasks and (little screens) disapeared

Dear all,

I have a strange problem and it is hard for me to describe it.

I run Debian edgy with KDE and my home is on a network. After a hardware failure, I switched to a machine running Kubuntu. Now that my old machine is back, I continue to run Debian. But now, a strange problem appeared:

After logging in the first time, I got an error message. This message does not reappear, so I cannot give it to you but I remember that it sayed something about the panel.

The problem is: The task bar does not show the little screens (the ones you click to switch) and the running applications. In other words, if I minimize winmdows then they "disapear" and I cannot reach them anymore. The attached picture shows my "empty" task bar.

I know, my description is not very precise. But I'm lacking knowledge and I'm willing to give more info if you tell me what you need.

Thanks,

Ulrich