Hi Ian,
It may be worth your while to create a Moodle Tracker issue with this problem, and relate it to SCORM. Make the bug type BLOCKER and with luck Dan Marsden may be able to help you before he clears off on holiday!
It seems pretty strange that everything was working OK and now isn't after setting up a SCORM course. I know Dan has been doing quite a bit of work with SCORM recently, so may be related to that. Javascript perhaps...who knows.
Have you tried just creating a new database and link your Moodle to it and restart the install by renaming config.php config-old.php At least then you would find out if your version of Moodle has been corrupted or not.
Mary