I have a course that when publiched as scorm 1.2 and uploaded to my Moodle 1.9 LMS works great.

If the same course is exported as 2004 and uploaded, it runs slow the first time and when you exit (whether you finish or not) on the next attempt to take the course it locks up IE(v7) every time.

Any ideas???

It seems m1.9 is not fully compliant yet. I had similar problems after upgrading from 1.8, then publishing in SCORM2004. So I shifted back to SCORM1.2 which still suits my purpose. There's some discussion here in the May 2008 post that work is still going on http://moodle.org/mod/forum/discuss.php?d=95946&mode=1