We currently have a user whose account locks out about three times a day for no reseon.
I used the tool lockoutstatus.exe and can see the account locking out and which domain it is locking out from (we have 3 domains)
When i look at the event logs you can see there was an error which is
Replication warning: The directory is busy. It couldn't update object CN="Hitchen, Paul",OU=Development,OU=IT
co,DC=uk with changes made by directory 7028d468-345e-45a5-9b39-df
o.uk. Will try again later.
For more information, see Help and Support Center at http://go.microsoft.com/fwlink/events.asp
That has now fixed itself but now I dont know why the problem is happening and how to resolve this issue.