Ah, the sting of an anonymous slap!
Well, to add more info for all you mind readers out there, I have actually found that the problem seems to lie with the combo of the Template Module and the Thread:Pool module. All I have to do is comment out "use Thread::Pool" and the non thread areas of the webapp work and the templates are all processed and displayed. I know, this isn't much to go on, but perhaps someone out there has seen something similar....