Hi Folks.
As described and found in this topic, the solution is pretty simple.
Put the lines
<%
If Not DotNetNuke.Security.Permissions.TabPermissionController.HasTabPermission("EDIT") Then
ControlPanel.visible = false
End If
%>
in the ascx-file of the skin, then the panel will be unvisible for all users but admin or host.
In the portal settings set the mode to edit as standard to give some specific users the appropriate rights for some specific modules
If nevertheless these users won't have the right (e.g. adding events to event-module, ADD-Link in bottom left corner is gone) then the same happened to you as it did to me. What it was? I don't know, but here is the solution:
Go into the table PROFILES and just delete all rows. Then they will be treated as new accounts and will inherig the right right: Edit as standard where allowed.
Honestly, this is not my solution, it came from John Mitchel.