ABORT EXCEPTION HUNT

I sometimes get the following error message
1280319 0 ABORTED Exception(24): 4 in seq:abortCallback
1280327 0 abortCallback for: [0xa21a4c8, line 0xa21a4c0]

I did some grep in the logTM code and found in TransactionManager.C there are two hits of "ABORTED Exception". One is in the rollback method and another is in the doAbort method. But which is the culprit and why this is happening are yet to be discovered.