What's the EventID/ProviderSID?
The ProviderSID is Microsoft-Security-Auditing 4742
I have been having this same issue and believe I have found the reason.
According to the LEM user guide, "A ChangeDomainMember alert occurs when an account or account container within a domain is modified. Usually, these changes are made by a user account with administrative privileges, but occasionally a ChangeDomainMember alert will also happen when local system maintenance activity takes place."
So if you aren't changing any of the PC attributes it appears that it's just local system maintenance that is taking place.