How can I suppress ""CryptoAPI Private Key" dialog to once?

From: cyberninja (cyberninja_at_discussions.microsoft.com)
Date: 01/25/05 

Date: Mon, 24 Jan 2005 17:43:33 -0800

If the signer certificate is set to high-protected when importing from a pfx
file, each time when I use Outlook 2003 to review one signed email, the
dialog box of "Signing data with your private exchange key" occurs several
times and keep on asking me to enter the password. If I select the check box
of "remember password", although I don't need to enter the password, the
annoying dialog is still there. I tried to create a registry key
"HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Cryptography" and manually
added the following values:
CachePrivateKeys=1
ForceKeyProtection=1
PrivateKeyLifetimeSeconds = 0x10000
PrivKeyCacheMaxItems = 2
PrivKeyCachePurgeIntervalSeconds = 0x10

Note that those registry settings coming from the doc for Windows Server
2003 and my system is XP + SP1. I read the link in
"http://msdn.microsoft.com/newsgroups/default.aspx?&query=CryptAcquireCertificatePrivateKey&lang=en&cr=US&guid=&sloc=en-us&dg=microsoft.public.platformsdk.security&p=1&tid=5c1bf406-3c9e-4ebc-9f35-93fa669ff4ca&mid=80d943d4-36de-4d71-b22a-bb3f16f355a5" but the settings does not work on my system.

Does any body give some suggestion?

Thanks

cyberninja