Auto gear box Limp-home mode?!?!?

Hi there I have a v8 auto 3.6 and the auto gear box every so often goes into something like limp home mode, just stats in one gear. I have noticed that it's happen in stop start traffic more than any other time. If you pull over and switch off and startup it's perfectly fine, it's as if it's getting confused. If I switch it to manual that's doesn't work either.

Has anyone else had the same issue? Or has any one got any ideas on what the problem my be?

I have checked other posts and can't seem to find anything about this problem

Thanks nick