Due to a bug in kpanel2 (just fixed on the cvs) your kpanelrc file
(under ~/.kde/share/config) may contain the following entries:

controldelta=...
Buttons=...
ButtonDelta=...
control=...

under the default section ([KDE Desktop Entries]). This is wrong, as they
should
go under [kpanelButtons].

If you have been using kpanel2 and you want to clean up your kpanelrc:

- upload kdebase/kpanel from the CVS (HEAD branch);
- edit ~/.kde/share/config/kpanelrc using a text editor and delete the 
  above entries from the [KDE Desktop Entries] section;
- run the new kpanel and make sure that after moving a button on the panel
  the above sections appears only under the [kpanelButtons] section.

If you don't follow the above steps, kpanel will work correctly. The wrong
entries, however, can mislead you during future manual editing of kpanelrc.

-- Pietro Iglio