Sorted it!
Uninstalled all things Apple - bonjour, mobileme, itunes, itunes updater etc etc. Then re-booted. Then re-installed itunes and everything is fine (funnily enough mobileme did not re-install for some reason but I don't need it anyway as it's accessible through the internet).
All my apple hardware works fine and I can now access mobileme and find my phone anywhere in the world, as well as send a message to it or wipe all the data remotely.
I think mobileme was the problem but I thought I might as well go for the full delete to try and sort the annoying boot up problem.
:D