By public page, do you mean the 'you've put ruby on rails' page? Or is it a page that you developed in Ruby that is backed by a database? From your post it sounds like you may not have a database set up, or it isn't configured quite right.
Is you database.yml set correctly in your /config folder? There are 3 settings in there by default. If you haven't changed your mode to development in your environment.rb then you'll be running in Production mode. That may be part of it there - I wouldn't be surprised if there were issues with generating scaffolding in production mode.
Active Record is trying to call symbolize_keys on a Fixnum, which doesn't have that method. There is a bunch of error checking in the method, but they were never expecting a Fixnum. Something is getting passed in wrong. I'd scour the database.yml pretty carefully -- I bet that or the mode you're in is throwing you off. Maybe you defined a development database connection not realizing that apps run in production mode by default at DreamHost?
You can look at exactly where the error is coming from in the source code here:
You'll see there's actually quite a bit of documentation near the method your looking for (establish_connection at the line spec = spec.symbolize_keys). This is one very nice thing in working with rails -- it's all right there. A little digging and you can find all the magic goodies.
And I have to ask... you do have a database set up, right?
Finally, I'd really suggest doing development on a local machine. It's pretty easy to get things going on your own machine and then just upload when you're ready to go into production. I've actually never tried to generate scaffolding on a DreamHost server.