We have done a lot of research into this behaviour of the Internet Explorer ActiveX control. The error page seems to appear under different circumstances, often when multiple web site portals are being loaded at once. But it does not always appear for the same URL or set of URLs. It is the browser that cancels the page load. We have not found a way to prevent this behaviour.
The reason the page eventually loads is that the Formativ Portal captures the canceled load, and reloads the page. This is our workaround/cosmetic fix – imperfect, but better than nothing!
We would appreciate it if you could inform us of scenarios that cause this in a repeatable way. We may be able to improve on the existing workaround with the benefit of more data on this behaviour.