[news.eclipse.platform] eclipse configuration corrupt - how to uninstall

["Michael Moser" <mmo@xxxxxxxxxxxxxx>]

I obviously have a corrupted eclipse (3.0.1) configuration:

In Help => Software Updates => Manage Configuration there is an
location entry there is a location that has a no-entry sign.

Underneath that are two entries that both also have a no-entry sign
PLUS a white X on a red square (as far as I know this indicates not
installed or at least not working).
The right pane of each of the two features offers Enable, Uninstall
and Show Properties.

When I click the Uninstall I get an alert that I first have to Disable
that feature (even though the right pane shows ENable, so I would
assume it is already DISabled, esp. since there is no disable link or
button).

If I click Enable then I get a box asking for confirmation to enable
that feature, I then get the alert suggesting that I should restart,
but regardless of whether I restart or just click "Apply Changes" the
feature is NOT enabled. So I seem in an endless loop here. How do I
get rid of such a misbehaving feature? How can I force an uninstall
(or at least a "forget")?

Michael