What is the GIS software you are using? Have you checked its website for a Firefox/Mozilla/Netscape plug-in?
NCompass Labs, per on google search, seems to have acquired by Microsoft. That could be the problem, since Firefox is giving MS IE a run.
NCompass doesn't seem to have a separate website.
The software is NACCRRAware, a Web-based information management software designed to collect, report, and distribute information for nonprofit groups. They don't have a plug-in. We were warned that we "had to use Internet Explorer" but, being stubborn and not a fan of Explorer, was trying to do something different.