SMD_AGT user getting locked frequently in Solution Manager

Hi, User SMD_AGT getting locked frequently within 1 hr,  in Solution Manager system 7.1 SP12. All the agents are registered with SMD_AGT user without any issue.I have also checked through RFC; credentials are fine. SM21 05:19:09 DIA  014 100 SAPJSF                      US  1 User SMD_AGT locked due to incorrect logon M  ***LOG US1=> Login, Wrong Password (SMD_AGT ) [sign.c      4862] No dump in the system for this isseu and nothing in the trace. Please suggest on this. Thanks, Harsh