ok... success

I manually wiped out the folder DesktopModules\Admin\Security and replaced it with the contents from the 8.0.3 upgrade package.

That made the login box finally show up.

I'll be doing the same for other folder as well just in case there are similar issues elsewhere in the system.
Regards
Rob

Yes, all unblocked etc.

I believe this may have occurred due to one or more copies of ascx files from 7.4.2 that were still sitting in the folder mentioned. These were backup copies of the modifications I had made to the originals. I'm guessing the application tried to compile them and caused some sort of conflict with the new files. It never had an issue previously, but obviously the changes are now enough to show it up.

I'm pleased to find my old replacement menu system still works fine in DNN8, but it looks like a datepicker change is causing a whole lot of module failures... mainly the various forms modules. This could end up being an expensive datepicker... erk

I'm also seeing double pages where an admin page had a new name. I'll try renaming them all back to the defaults before I do the live update.
Regards
ROb