If I am in the pool school and click on the pool school link, I get directed to pool-school/pool-school/ which gives me a "The requested topic does not exist." error. If I click on the link again, I get a 404 error. I found this when I was looking at an article and wanted to go back to the Pool-School main page to look for more information.
I may be wrong, but I think pool-school should bring me to the Pool-School page, but it gives me a not found error. I have to add the final '/' to the URL to get it to work.