Hit another Gotcha with CRM 4.0 today when enabling the Outlook integration – when you install it under 64-bit, the odds on it will insist that you do not have Outlook installed, or it is not your default mail client.

To get round this, you need to tweak the registry a little:

Change the default value in both these keys to “Microsoft Outlook”

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Clients\Mail
HKEY_LOCAL_MACHINE\SOFTWARE\Clients\Mail

And restart setup.

Problem solved :)