Hi James,
Did you change the alias name in the portal alias db table? If not, Select Admin|Site Settings|Advanced|Portal Aliases and adjust the canonical portal alias to localhost (or your configured portal alias).
Or the issue may be the way the files were copied or the folder path may be different locally than on your live site. If you moved servers and your new server/database uses a different objectqualifier on db objects then you will need to add that to all the objects (tables and stored procs).
To get a development site exactly like your existing site that you can test in first please see the following post on "HOW TO MAKE A DNN SANDBOX TO PLAY IN IN ABOUT 10 MINUTES": http://www.smith-consulting.com/Forum...
Thanks,