Desktop not loading

[Peter Baily]

I do not know whether my problem is related to the long running thread
of correspondence about desktop problems.   If I have missed something,
my apologies.

Regularly - and again today- when I start Ubuntu the desktop (one of my
photos with media icons superimposed) does not load.   The bars top and
bottom with their icons load normally leaving a black screen.
To correct this I have to reboot probably twice and some times three
times - this morning two reboots.
The loader must be skipping an instruction intermittently.   Please, can
anyone offer a cure?   I would hope not to be wasting time like this in
future.

"Peteralchemist"