I've seen a pile of ESENT errors (logging every 30 minutes) on a Windows XP system with SP2. This has to do with the Windows (automatic) Update service. This system is set up to check for, and download updates, notifying the user prior to installation.
Once these errors (and there are tons of them) show up in the event log, I found I could no longer check the update preferences (Control Panel, Automatic Updates). Double-clicking on the icon generated DCOM error 10010 in the System Event log containing a GUID and a link to the Help and Support Center. In this instance, the link is useful; pointing to an article that describes how to identify the vendor who owns the GUID. Turns out, the GUID is the automatic updates, but was still a useful exercise.
Cycling the Automatic Update service allowed me to access the update preferences again, but logged an ESENT error within seconds and every 30 minutes thereafter. As soon as the ESENT error appeared, I could not access the update preferences in control panel until I cycled the service, and the DCOM error showed up again.
I shut down the Automatic Updates in the update preferences UI, which in turn, cycled the service, leaving it in a running state. Not sure why the service would to be running if the system isn't set to check for automatic updates; but there's a method to my madness: This let me confirm the ESENT errors are not caused by of the service, but by the check for updates action the service enables.
This means that if you're not checking for updates, you can disable the service and rid yourself of the ESENT errors. This doesn't solve anything as it does not address why the update checks generate the errors, but helps to identify the playing field. More as it happens.