Hello mommiesugar -
I'm sorry to hear about the difficulty you encountered with the site and category selection on the lister page. We were experiencing some intermittent issues earlier today which have since been resolved.
Should you encounter further difficulty, please feel free to let us know what you run into in a support case, which you can file from under the Help tab of the site and we'll be happy to look into it further.
Apologies for any inconvenience this may have caused.