The %PLATFORM_UCAST-3-ADJ: error message occurs in very rare conditions when a continuous MAC address change is reported for an adjacency. This message appears when the adjacency module for unicast routing encounters an error. Typically, this problem is due to an incorrect network configuration.
This error message can occur in switches that run Cisco IOS Software Releases 12.1(14)EA and 12.1(19)EA.
To resolve this problem, upgrade the software to Cisco IOS Software Release 12.2(18)SE or later.
For additional information, refer to Cisco bug ID CSCed08256.
For the latest Cisco IOS versions that are available in the 12.2.25 train, refer to IOS Upgrade Planner.