(For sub: I was calling UiList.SetListObjects(items, -1); I honestly can't remember why, but I think it was something to do with not knowing what list element should be selected, hence the -1. That obviously doesn't work anymore, so I've called it with 0 instead).
Thanks Iain (and Sub) That has definitely fixed it for me. Now running with all the latest patches and no problems. - Apart from Windows 8.1 Update 1, but that's another story
It's not an overly complicated system - it's more - overly simple operatives