I recently switched to Vista and Office 2007. I set-up Outlook with the details of my email certificate. The trouble is, whenever sending a message, Vista pops up a dialog asking whether to grant or deny permission to the certificate. The exact text is:
“Grant or Deny this application permission to use this key”.
The way around this is to not use Outlook to install the certificate but to right click on the certificate in Explorer and let Vista install it. Another important thing when doing this is to NOT click the Strong option – this is what causes the prompting – leave it as Medium.
To reinstall the certificate: