I have been playing around with this for some time now.
Eventually I recreated my Eclipse install excluding WTP (eclipse Web Tools Project), and then imported the projects.
Things seem more stable now.
Can anyone confirm there is a conflict between JBoss IDE and WTP to put my mind at rest.
Spoke too soon.
Problem is back, everything is fine (even hitting breakpoints) then all of a sudden bang.
I am completely lost now!