Since switching my everyday PC over to Windows Vista, I’ve been unable to reply to any e-mails using Outlook Web Access (OWA) whereby the reply pane opens, but the ActiveX control doesn’t load. I tried various browser settings before a bit of googling turned up a thread on the microsoft.public.exchange.admin newsgroup that seemed to describe an annoying “click to activate the control” message that I’d been experiencing with fully-patched Windows XP clients (caused by the Internet Explorer update described in Microsoft knowledge base article 912945).

Microsoft knowledge base article 911829 describes the problem as well as highlighting that Windows Vista does not support the ActiveX control used by OWA for HTML editing. Once I’d installed the associated hotfix on my Exchange Server 2003 server the issue was resolved for both my XP and Vista clients.