[Zope] Problem solver tracker

Hi, Anybody who has already made a problem solver tracker? Or knows about a product which I can use? Basically we should be able to allow a user to define a problem. Other people can write follow ups and replies There should be some restrictions on which comments the user can see. Has somebody some hints on that? Thanks in advance! It would be helpfull in my struggle to convince people here about Zope and Python if I find a rather quick solution, so any hints are welcome! Regards, tom.