I have also seen problems with ports going down on 2900XL-EN switches with no recovery short of wipping out the config. In my environment, the scenario involved the switches running 12.0.5-XU code with a cabling plant including IBM Type 1 connections. With the Type 1 connectors, since they were designed for Token Ring and automatically wrap around the internal wires to prevent breaks in the ring, when used in an Ethernet environment the wrap arounds can cause a switch's BPDUs to wrap around and come back to its source port. When that happened on our 2900's, the affected ports shut down and could not be recovered despite trying the shut/no-shut routine, cold starts, reloads, etc. Under 12.0.5-XU, the only recovery we had to get those ports back was to blast away the config and re-start the switch. A subsequent release of 12.0.5(2)-XU provided a fix for the situation.