Hyperlinks spawn new window with two tabs

Our project team has encountered a mind-numbing issue and it's time to reach out to the community.

We've discovered that when opening our Captivate 8 published output (runtime), in a new window, from an existing browser window using the window.open method, in IE10 (got all that...?)

...hyperlinks (secure or unsecure) to URL's outside of our company domain, configured to open in a new window (via the Insert Hyperlink dialog), do indeed open in a new window, but there are two tabs. One blank tab, one tab with the requested URL in a new browser window.

If we access the Captivate content directly (open browser, type url, press return...), URL's open in a new window, in a single tab, as expected.

Thoughts?