Multisite /blog in permalinks

Hi,

I'm running a multisite wordpress install. Only one site so far, located at root.

However, for some reason I'm getting /blog added on to all permalinks on that site. How do I turn this off. If I manually change the permalink string under Sites->Settings in the network admin, it gets rid of the /blog/ but this returns if I change any of the permalink settings in the site admin.

Any ideas?
Chris