If you want a Really Quick Hack that will Probably protect you from what the other kids are doing...

Write your own code inside a package, use strict in your code, and explicitly reference the globals in package "main" which they seem to have claimed for themselves. As long as you're in a different package, and don't create any globals in main::, you should be Okay, no? (until they step on each others toes instead of yours... but to a certain extent you're never going to be able to fully insulate yourself form stupid programs or programmers)

Alan