We have (2) Cisco 5509s with dual SUPIIIG. They are linked via GBIC modules in port 1/1 and port 2/1. The dual links are setup in trunk mode, full duplex, speed 1000. We have been getting a lot of FCS Errors and RCV-Errors on one of the GBICs. Over the weekend the GBIC in question caused the entire network to go down because it appeared to be flipping and we received many MLS-4-MOVEOVERFLOW:Too many moves, stop MLS for 5 sec errors. We already replaced the GBIC once and thought the problem was solved. I checked the traffic on the switch before the outage and there was only 20Mbits of traffic crossing the links. What else should I look for to solve this issue?