Reminds me of my high school days, though I don't recall the software being named Fortress. I'm thinking it was something else, but same idea. Eventually the teachers gave a small group of us formal access to disable it as they realized we weren't out to be malicious, only wanting to make full use of the computers.
My school used one called "PC Lockout". It wasn't long before the necessary DEBUG.EXE commands to switch a strategically chosen JNZ to a JZ were being distributed.
