No 'skin_garage_external' skin was created. I'm using the Cleancut skin which came with 3.1.0 and that's now my default skin so I've removed the actual default one, looks like you've identified the problem!
Would you be kind enough to go over the work around in more details, I'm not sure exactly what you want me to do! Will uninstalling and re-installing the garage (not news!) system delete any data?