This is related to issue 3695.

https://hudson.dev.java.net/issues/show_bug.cgi?id=3695

That particular bug has been fixed, but it highlighted a more general need that
would be handy for the "run slave as a service" functionality.

Quoting from issue 3695:

"In order to have Windows services be able to interact with the desktop, they
need to run as the System account. Since the System account has no user profile
(which Selenium RC wants), it is necessary to use something like SysInternals
psexec utility which can run a process as a different user. This allows us to
launch Selenium RC as a proper user account and then tests run properly. "

If there were an option to start a process as another user, then it would be
possible to use SeleniumHQ while running as a service under Windows without
having to give up using the Hudson plugin and just writing batch files to do the
work.

I think that this could be useful in more places than just the Selenium plugin
though, which is why I filed this as a general enhancement request.

Thanks