Jenkins as a Windows Service keeps losing elevated Privileges

[PortMan]

We recently tried moving our Windows Jenkins slaves to run as a service instead of just running the slave agent jnlp file.

According to the Mercurial Plugin (https://wiki.jenkins-ci.org/display/JENKINS/Mercurial+Plugin),

"The default installation runs windows service with "local system" account, which does not seem to have enough priveleges for hg to execute, so You could try running Jenkins service with the same account as TortoiseHG, which will allow it to complete."

This we did, and it worked. For a while.

But sometimes after there was a disconnect between the Jenkins slave and master, it would stop working. Jenkins would call mercurial and it would hang, just like it would do if the service was running with the "local system" account.

I could sometimes get it to start working again by restarting the Jenkins service on the slave. But somtimes I'd have to go back in and re-set the service to run with an elevated account.

Has anybody else experienced anything like this? Is there any way to keep the Jenkins Service running with elevated priveleges?