"iChat can't communicate with the jabber account, disconnected unexpectedly"

We are running a Snow Leopard server here in the office, but no one can connect to iChat with their given jabber id. I have tried manually putting the settings in, I have tried letting the computer configure them itself [through system preferences -> accounts -> login options and choosing the networked server. I'm have gone into the server itself and made sure everything is on and functioning, but it just won't connect. I keep getting the same message.

"iChat can't communicate with the Jabber account "gretchenmiller@marquardtplus.private". Disconnected unexpectedly"

I've looked through the community and none of the given directions have helped. Can anyone out there help me out? We're a small design studio, so we don't have an IT person to do this for me.

Thanks,

Gretchen