Are you using SNMP on your device. If yes, are you polling mib "dot1dTpFdbEntry".
Since this is on SRD1, you are most likely running into a software defect# CSCsz22137. This is a cosmetic defect and shouldnt have any impact.
I would recommend you to upgrade the router to SRD5 or later release.
As a workaround, you can stop the polling of mib "dot1dTpFdbEntry".
Hope this helps.
Regards
Vinit
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Thanks
--Vinit