Event ID 4625 being logged - bad username or password

Event ID 4625 being logged - bad username or password

Hi.
 
We are running ServiceDesk+ 8.1.0 (build 8101) on a Windows 2008 R2 server and keep seeing Event ID 4625 logged in the Security Event Log - the account name is shown as a single Chinese (I think) character and the reason for the event is "Unknown username or bad password".  This appears to be generated by E:\ManageEngine\ServiceDesk\jre\bin\java.exe
 
Here is a screenshot of the error:
 
 
Has anyone else come accross this before, or have any suggestions as to why this is happening?
 
Many thanks,
Dave

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