As I mentioned in one of my other posts, each developer in our SharePoint team runs an independent farm on a project-specific Virtual Machine.
One of our newer developers reported that, when they tried to create a subsite at a level 2 levels deep, the site was created, but it was created under the root site (only 1 level down).
It turns out that this was because they were accessing the site using "localhost", instead of the NetBIOS name of the server.