New
#11
Re-image from porty hard disk seems to have worked and after several reboots this morning the system retained the ability to "save as" in various applications without any problems.
From checking the dates it looks like the image was taken mid way between installing my new GFX card and installing SP1, so I think I'm probably safe to assume the SP1 install might have been responsible for borking those two DLL files, as theres nothing else I can recall having updated or installed during that period.
Next trick now will be a case of very carefully applying any updates/etc again in safe mode this time, and waiting to see which of them, if any, breaks the system again...