All of a sudden out of the blue, we started getting the "The tree or server cannot be found" error. I work at a k12 school and it first started at just one of our elementary buildings. After a few days it seems to have spread to our other elementary building. It also appeared to strike randomly, meaning sometimes the machine that couldn't log in five minutes ago can now log in. What initially fixed the problem was changing the tree name to be the IP of one of our servers. I assume this means that it was an SLP problem.

Rather than manually configuring the SLP settings on each machine or pushing them out with ZENworks, I opted to fixed the problem by configuring an SLPDA on one of our NW6.5 servers and I pushing out the client slp config via DHCP.

My question is, what could have caused SLP to stop working via Multicast in the first place and why did it only affect two of our 5 buildings?

Our network consists of Gig Fiber between all buildings and we run mostly cisco equipment with a few 3Com switches thrown in here and there. As well as some unmanaged 5-8 port Allied Telesyn switch in the classrooms.

Any Ideas?