I have a site that is created in .Net Nuke... It does a weak url rewrite like so: test.com/test1/test2/tabid/679/Default.aspx Every single page ends in default.aspx, my theory is that google is looking at these pages and seeing that the path info is always default.aspx and getting urls mixed up. The reason I think this is because some times pages descriptions are mixed up versions of the current page the home page.