Clients not getting correct dock

I am not sure if anyone else is getting this, but at one of my elementary schools we have installed a new dual core intel xserve and have two labs of dual core intel imacs. When the students log into the lab intel imacs occasionally 5 to 15 of them will get the admin dock, they get their documents and group shared folders but they do not get the appropriate applications for the workgroup. They have to log out, restart and then log back in, that seems to get them the right dock. Any suggestions would be helpful.