Does this only occur on IE or also on other browsers?
Since JS can't start a system shutdown, I'm quite puzzled...
Our help is presented in a custom help shell that opens automatically in IE, so testing in other browsers isn't straightforward. Plus, the script error is a bit intermittent. I'll attempt to redirect the browser call to a different browser, by some means, and see what happens.
I found some info about this error message here: Unknown Error!! - Support - AutoHotkey Community (Although it is not directly related to RoboHelp.)
According to that forum, my "translation" is that this error message has to do with Internet Explorer still running in the background but trying to shut down. (It's all in English, I just mean translating from geek-speak.)