Site/CMS generating pages on its own

I'll try to provide as much info I have about PHP and MODx versions we are running, as I'm a user and not a programmer. Our developer left the company, so I'm doing the best I can on my own. Here's what I know about the web server, etc:
Web Server: running PHP version 4.4.7, Apache version, Linux system
Database: MySQL (no idea what version - sorry)
MODx: version 0.9.6.1p2
Browser: Firefox 26.0
Operating System: Mac OS X version 10.9.1

Anyway, we developed a site for our client over 5 years ago, so I know it's older. We've not run into many issues with it, but we're having an odd issue right now where the site/CMS/whatever will randomly generate pages (and cache them) with links to style sheets and other elements prepended with a non-existant directory. Which means that some of the pages will not appear correctly all of a sudden. The website is www.harrisonburgdevelopment.com and an example of the links we're ending up with follows:

<link rel="stylesheet" type="text/css" href="/econ_dev/assets/templates/citytemplate/layout.css" media="screen" />
<link rel="stylesheet" type="text/css" href="/econ_dev/assets/templates/citytemplate/print.css" media="print" />

Instead, they should appears as

<link rel="stylesheet" type="text/css" href="/assets/templates/citytemplate/layout.css" media="screen" />
<link rel="stylesheet" type="text/css" href="/assets/templates/citytemplate/print.css" media="print" />

It's adding a "econ_dev" directory and trying to link to that non-existant folder, so my pages do not show up right. As of this morning, all the pages look fine, but it will randomly generate them from time to time, causing much frustration to my client. Any ideas? Or more specific information I'd have to find out for anyone to be able to help me?

Thanks!

- Dawn Driscoll

What does the .htaccess file in the site root look like?

My apologies on my ignorance, but I'm not sure where to find the .htaccess file via the CMS. Where would I look for it? Is it under Resources or the Directory Listing? Thanks!