This now appears in every page I load in Moodle (in Internet-Explorer-8). I realize that client-wise this warning should not be suppressed globally. If this cannot be updated server-side, is it possible to blacklist individual websites? 
E.g. if you want to update your email start page from http://unccmail.uncc.edu to http://mail.uncc.edu.
in Safari, go to menu: Safari / Preferences / home page: type your updated page address in here and click OK. Visual walkthrough is e.g. here: http://www.youtube.com/watch?v=VIGocolMtzU.
Similarly in the preferences of all other common web browsers.
Try pressing the CTRL-key when clicking a link that tries to open a popup window.
This is a known problem with web-based learning applications like Moodle or library ereserves (like UNCCC’s Docutek ERes-based one) .
You can permanently disable popup blockers for certain sites if you study the documentation that comes with your browser (and possibly with the shared computer) you are working on.