I'm creating a certificate to use with an SslStream, and I've been doing it this way under XP:

makecert -r -pe -n "CN=aName" -ss my -sr localmachine -sky exchange 
  -sp "Microsoft RSA SChannel Cryptographic Provider" -sy 12 server.cer

If I understand this correctly, this creates a certificate in server.cer, and creates a private key for it in my personal certificate store. Once I have done this, I can create a certificate object like this:

X509Certificate.CreateFromCertFile(certFile);

I then use it with the SSLStream, and everything works fine.

Now that I have switched to Windows 7, the private key seems to be disappearing every time I restart the machine. I run a command prompt as Administrator, and execute the same makecert command shown above. This succeeds and the SSL connection works correctly. If I restart the machine, the call to AuthenticateAsServer fails with the exception "The server mode SSL must use a certificate with the associated private key."

Why is the private key disappearing? What do I need to do to make it stick around?