Group: microsoft.public.windowsupdate
From: =?Utf-8?B?QnV6ekxpZ2h0eWVhcg==?=
Date: Tuesday, October 23, 2007 7:47 AM
Subject: RE: Boot problem after installing the new update KB941649

I had this problem too.

Installed KB941649 as suggested by a Microsoft Solution, and on reboot
windows hang on progress bar.
I restored system settings using Recovery DVD and Windows started properly.

I have AHCI enabled too. I agree this can be the cause of the problem.