I ran into an issue today where What's Up Gold was showing interfaces down that were up in the switch.  In What's Up Gold each interface is referenced by an index number that is dynamically assigned by the IOS on startup.  The problems begin when a router or a switch are rebooted.  It dynamically assigns the interfaces an index number and it may or may not be the same as the index number before.

To fix this issue under global config mode type the command- Switch(config)# <strong>snmp-server ifindex persist</strong> then issue a <strong>copy run start</strong> to save the config.  Now the index table is saved with the running configuration and will keep the same index number during a reload.  