Let's try something basic here before we get too far into this.
Deactivate the PowerPress plugin. Leave it deactivated for two minutes and then reactivate it. See if that allows for the http://www.geekgirlauthority.com/category/shows/booze-phasers/ URL to work as expected.
Don't panic! All of the PowerPress settings are stored in your WordPress database and won't be lost. I'm hoping that doing this will cause PowerPress to let go of that URL and give the podcast feed for that category a different slug.
