With the understanding that you cannot access the equipment, and that the individuals who set it up are not responding to you, maybe you should break into the router and switch. There could be a configuration problem that might cause this entire prob...
Well, you might have a faulty 2950. You might want to restart. If that doesn't fix your problem, then replace it if at all possible. I have also had the same problem as you, though it was on a larger scale. We couldn't figure it out for the longest. ...
Peter if you don't mind the question. What type of 4006 do you have? I have a few of them on my network and I have only seen them with the Cat OS.. I.E. Set commands.. not the Native "conf t" commands. Please correct me if I am wrong.