IE explorer OLE / com lockup in an MFC application

Can anyone provide insight into why the IE Control in our application randomly, infrequently locks up.

Because we don't have access to our customer's computers, especially not in a debuggable state, this one's proving really hard to pinpoint.

This is an MFC, MDI application where several report windows (10 or so) each subclass an IE control and display marked up HTML, except when the problem occurs where no report window displays a (new) report until the application is restarted.

Two lines of enquiry - one of the report windows is a Start Page which shows product information, as such it's constantly running javascript that updates the page every so often. (One of our devs has seen javascript errors from this window too). Is it possible to get some sort of threadlock between instances of the control?

Architecturally, is our implementation right? Would it make more sense to implement one instance of the control for the whole application, and have it open multiple windows? Having only the briefest of looks at the APIs for this object I'm not sure how I'd do this.

Thanks for looking!

What I have tried:

Turning off the javascript from the front page of the application.
Trying to reproduce the defect in debug code

Tags: MDI, Explorer, Lock