JavaScript Error

Hello -- I have a course that was published as AICC.  We have loaded the course into our LMS (Plateau) and there have been over 3K course completions.  Several users, however, are receiving a JavaScript error when they submit their test score and "Finish" the course.  I am stumpted as to why this is happening for only some users, and not everyone.  This is a high profile course and this error is attracting a lot of attention from upper management.  Has anyone else ever experienced this?  I know it's probably a local system issue, but I'm not even sure what to check for -- any help is appreciated.  Thank you!