Yikes! Panel disappeared; Won't start from 'settings', either (F14)

[Ron Leach]

List, good afternoon,

Switched on netbook as per usual today, login, but then there's no 
'panel'.  I can right-click on the desktop, navigate the applications 
to 'XFCE settings' but when I click on 'panel' nothing happens. 
(Other settings 'applets' work fine.)

I've gone through Display, Desktop, Window manager etc, these settings 
all seem fine.

My guess is the 'panel' applet isn't running.

Bit of a problem, because I use the network item on the panel to 
select a network for connection.

Another clue, at login screen, there is a 'panel' which shows language 
and keyboard selectors.  After login, though, the panel disappears and 
doesn't come back.

I know that this is F15 testing day, but hadn't realised my netbook 
knew, too. :)  More seriously, could anybody hint what I should check 
to see why the panel isn't coming up?

I'd like to double check that it isn't caused just by a 'desktop' 
switch, could anyone also let me know how to switch desktops when the 
panel isn't there?

Sorry for the so-basic questions.  Both F13 and F14 have been really 
reliable for me on netbooks, and so I don't know enough to 
troubleshoot them.

Very many thanks,

Ron