Portfolio Issues

I’m currently wrestling with a tricky problem, and could really use some help.

I’ve set up a photo gallery with WordPress, using the WordPress portfolio. Since I don’t like the word “portfolio” (I’m a photographer, not an ad agency ;), I looked for a way to change it to “photography”, and found a solution here:
http://thesisthemes.com/support/discussion/1922/can-i-change-the-portfolio-slug-to-something-relevant-to-my-portfolio-for-better-seo/p1

I also set up a page as /photography, and that worked fine as well (no collisions).

Today, however, I tried to set up a child page under “photography” (like /photography/gallery/) and all of a sudden, WordPress is throwing me 404 not found errors.

– When I remove the child/parent setting and set up /gallery/ one level higher, I have no issues.
– When I remove the hack above that replaces “portfolio” with “photography”, the /photography/gallery/ child page will show up fine as well.

But for some reason, WordPress doesn’t like the combination of these two.

Does anybody have a clue why this is happening, and/or how I can run the portfolio as /photography/ directory AND set up child pages under that same directory, so my setup looks consistent? Is my best bet to just leave the WordPress code untouched, set up everything as “portfolio” and do a rewrite on the server level?

Thanks!