Reported by dave090679 on 2010-03-16 18:59
When I open Child windows in various applications, navigation
inside these child windows is impossible. After a few seconds, "no
response" is displayed in the title bar of the application and the
only way to quit the application is the processes tab of the task
manager:-).

Examples for such hanging applications are the dvbviewer and nvda
(the effect also occurs when I try to open nvda's own dialog
boxes). In dvbviewer, this occurs when I open the epg, the channels
list of the options dialog.

Primarily, this effect occurs in windows 7 and Windows Vista. But
you can reconstruct it in windows xp by installing the kb971513
windows update which is available in the optional software
category.
This eror is architecture-independent. It occurs in windows 7
64-bit and in Windows xp 32-bit (when kb971513 is installed).

In the MS knowledge base, I read that the kb971513 is an update for
the UI automation libraries for Windows xp and Windows Server 2003.
So I guess that this effect is a conflict between NVDA and UI
automation.e