This problem affected access to our servers between sometime early this morning and about 9:50AM. It didn't isolate the servers but it would have slowed things down as this was a loss of half of our bandwidth for the servers. Some time last night, someone it would seem at US West because they provide the access circuit; put our CSU/DSU for one of our Sprint T1's in loopback. This has been an ongoing problem recently; we know the CSU/DSU isn't spontaneously going into loopback because I have rolled it with another circuit and the problem stays with the circuit. A couple of possibilities exist; someone at US West may have a service order with the wrong info on it and are getting into our circuit; there may be a noise problem automatically generating tickets resulting in testing; or there may be some fault in a DACS switch or SMAS access switch, and there are other possibilities. I talked to a Sprint engineer today and they are working with US West to identify the cause and correct it.