With this SCORM object:
http://moodle.org/mod/data/view.php?d=50&rid=4083

when navigating through the object, the items in the TOC become duplicated and invalid items in the TOC are displayed causing a 404 error if you attempt to navigate to one of the "duplicated" Items.

on first load of the object, the toc lists:
2-1-1 Quick Facts
2-1-1 Quick Facts Ex. 1
2-1-1 Quick Facts Ex. 2
2-1-1 Quick Facts Ex. 3
2-1-1 Quick Facts Ex. 4

If you click on a link to another item in the toc(or use the navigation), the list becomes
2-1-1 Quick Facts Ex. 1
2-1-1 Quick Facts Ex. 2
2-1-1 Quick Facts Ex. 3
2-1-1 Quick Facts Ex. 4
2-1-1 Quick Facts
2-1-1 Quick Facts Ex. 1
2-1-1 Quick Facts Ex. 2
2-1-1 Quick Facts Ex. 3
2-1-1 Quick Facts Ex. 4

original comments from Teresa
My student has completed each page of the SCORM - there are green ticks for each page in the results. Initially my student's second attempt looked just like a continuation of the previous attempt. After another few goes I managed to get a second attempt for a student but then got an error (using both FF & IE).

I created a video of the testing for you (because I've got a massive headache & couldn't be bothered writing stuff down!) - URL: http://coursecast.its.waikato.ac.nz/CourseCast/Viewer/Default.aspx?id=8bc24fcc-9b9b-49a9-a579-aa8701d80525
I have just realised my narration didn't work as I selected the wrong sound input and it needs a little editing but my head hurts and it's 4:55pm NZ time so I'm going home & you get it as-is!!

Below is examples of the lines I see in the error log duplicated in parts - hope they're useful to you
[Wed Aug 11 16:12:55 2010] [error] [client 130.217.159.104] File does not exist: /home/teresag/public_html/moodle20/mod/scorm/undefined
[Wed Aug 11 16:13:00 2010] [error] [client 130.217.159.104] File does not exist: /var/www/moodle/assets, referer: http://mdldev.its.waikato.ac.nz/~teresag/moodle20/mod/scorm/player.php
[Wed Aug 11 16:19:06 2010] [error] [client 130.217.159.104] File does not exist: /var/www/moodle/assets, referer: http://mdldev.its.waikato.ac.nz/~teresag/moodle20/
[Wed Aug 11 16:19:16 2010] [error] [client 130.217.159.104] File does not exist: /var/www/moodle/assets, referer: http://mdldev.its.waikato.ac.nz/~teresag/moodle20/course/view.php?id=8
[Wed Aug 11 16:20:13 2010] [error] [client 130.217.159.104] File does not exist: /var/www/moodle/assets, referer: http://mdldev.its.waikato.ac.nz/~teresag/moodle20/theme/yui_combo.php?3.1.1/build/node-menunav/assets/skins/sam/node-menunav.css&