Core issue
When multiple ports are configured to have duplex mismatch with the peer, and under heavy broadcast or multicast traffic, the VLANs disappear after a period of time.
This problem is not seen if the duplex mismatch condition is corrected after 15-20 minutes.
This is a mis-configuration issue, not a software issue.
Resolution
There is no workaround. Correct the duplex mis-match problem.
This issue is documented in Cisco bug ID CSCed08716.
