Windows Vista and Internet Explorer 7 fixed a security hole that had plagued the browser for some time, however in doing so Microsoft broke some functionality in Outlook Web Access. Last month Microsoft released an update to both Exchange Server 2000 and 2003 that enables OWA support for IE7 in Windows Vista. 

But it would seem that many people have not applied the patch and are still having issues with OWA and Vista/IE7. A recent [post on the IEBlog][1] attempts to handle the issue with a more thorough explanation.

The [original problem][2] involved a DHTML Editing Control vulnerability. IE7 (and a patch for IE6) introduced a change in the way the browser handles web pages that use ActiveX controls and Java applets such that a remote code execution flaw was fixed.

Unfortunately in the process of patching the security hole, OWA, which relied on the old-style DHTML handling, ceased to work. However, last month's Exchange Server patch should get things straightened out.

If your server does not have this update applied, OWA may not work with IE7 in Vista. Instead of the compose window you'll see a red "x" in your e-mail message body.

A couple other items of note in the recent update:

*	Fixed inability to edit replies to messages composed in Entourage Exchange client
*	Fixed inability to edit replies to meeting requests

If you are running into problems with any of these issues, installing the Exchange Server update should fix the problem.

[1]: http://blogs.msdn.com/ie/archive/2007/03/14/using-outlook-web-acess-owa-on-ie7-and-windows-vista.aspx "Using Outlook Web Access (OWA) on IE7 and Windows Vista"

[2]: http://msexchangeteam.com/archive/2006/11/16/431521.aspx "Recent change of Internet Explorer 6 behavior in handling ActiveX controls and its effects on OWA"