Won't stop Loading...

[kenw232]

I have a perfectly working Roundcube Version 1.1.3 installation.  But for a few users here and there it just its on Loading... when viewing messages the Inbox.  Does anyone know why? What would I do to debug this problem?  I've turned on logging but see nothing strange.  It works fine for one user, but the other don't.
I'm completely lost.