Newbie: base_url?

[eluser]ShawnMA[/eluser]
I've searched the forums/web and have been able to find what I assume is a quick and easy answer to my question. I just started working thru the 2 video tutorials and hit a small snag. In tutorial 2 (blog), whenever I attempt to use scaffolding or the comment_insert function my pages always double up the URL so I always get a 404 error. For example: http://localhost/CodeIgniter/index.php/b.../blue/view

I'm developing locally, and have my base_url setting to nothing (""). What do I need to config to ensure my pages always go to the correct location (and don't double up the url)?

Thanks in advance for your time and assistance.