Windows 2000 trusts

I work in a classroom environment and the entire structure of the room is built on a parent domain and many child domains. They each have transitive trusts with the parent domain. For some reason, I get frequent problems where a child domain is broken from the trust relationship. When that happens of course, he can't access anything in the Directory and verification of trust fails. Does anyone out there have a similar problem like this? It seems to happen on its own sometimes...