Cavedude - you are indeed a dude.
It was the maps.
I had downloaded and expanded them - but they were still in thier sub-folders. Made me feel like a numpty - but I'm glad to say it is working.
My wood elf druid logged in a crushbone and was immediately mashed to bits.
If you can say - what's in the map files that made the difference? I assumed that the map files I had already downloaded were working as I had no error from the client when I logged in - the map looked ok - it was the mobs behaviour that was odd.
Cheers