I too have spent a few days trying to configure this thing.
Here are some problems and their resolve:
1) First the zip program unloaded all of the files into one folder, so path names became invalid:
Resolve: I used WinRar to unzip – got that tip in these forums – thanks!
2) Files were missing after the FTP upload. Probably due to a time out or break in connection.
Resolve: Checked files and uploaded missing files.
3) The database I created had a different name to the directory I had created. Now this may sound really basic, but I was getting exactly the same error messages that were mentioned here. I re-checked installation procedure and nowhere does it say that the database name should be the same as the directory name – eg if WordPress was uploaded into your directory as /blog, then the database should be called ‘blog’ – well I am assuming this, because when I created a new database called ‘blog’ KAZAAM! I got a welcome message!
Resolve: make sure database and directory name are the same – I think.