Text Entry stalls module - why?

Hi there,

I've created a module using Captivate 6 (published as SCORM 1.2 for LMS use) and it has one slide where the user is required to enter text (simply the word Richard and not Case Sensitive). Some users have reported stalling happening on this page: they can click inside the textbox but they can't actually type anything.

I can't confirm the actual behaviour of the stalling because I don't have access to the users nor their LMS. What I would really appreciate is the following:

1. What are possible causes for the stalling?
2. What are questions I can ask the user to help isolate the problem?
3. What are known issues/best practices around file setup to ensure stalling doesn't occur? (my file has 69 slides)
4. Is there any relevance between stalling and the server setup?

Also, the LMS is Cornerstone OnDemand.