Hi,
After you registry the service, does everything go well?
When the service disappears in the Services.msc list, you should go to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services
to see if the service shows there.
If the service is in the registry, go to re-registry the service. If the service isn't in the registry, you need to manually install the service.
It is suggested that you can disable or uninstall the third-party antivirus software, since it may be the cause, which will remove the service when running a scan.
In addition, if you want to know why your registry is modified, you can enable the audit of the registry:
http://www.itprotoday.com/management-mobility/how-can-i-audit-changes-registry
Note: this is a 3rd party link, we don't have any warranties on this website. It's just for your convenience.
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