Java-administrator password keeps getting locked

Hi,

We have a portal 7.3 in which the Java-administrator password keeps getting locked. I can't see anything in the log traces in NWA. The only thing I've found is in security_audit logfile which doesn't really say much:

#2.0 #2014 07 17 05:47:03:913#+0200#Info#/System/Security/Audit/PrincipalModification#

#BC-JAS-SEC-UME#com.sap.security.core.sda#C000AC142D1F08D90000000000003284#52888950000000002#tc~bl~txmanager~plb#com.sap.security.core.util.SecurityAudit#Guest#0#JTA Transaction : 127261#040FAA9B0D6511E4C5A4000003270576#040faa9b0d6511e4c5a4000003270576#040faa9b0d6511e4c5a4000003270576#0#Thread[RMI/IIOP Worker [0],5,Dedicated_Application_Thread]#Plain##

User account modified    | USERACCOUNT.MODIFY    | UACC.PRIVATE_DATASOURCE.un:Administrator    |     | SET_ATTRIBUTE: islocked=[true], SET_ATTRIBUTE: lockreason=[1]#

Please advice,

Thanks.