Hi, We have a Web asp.net application running in the framework 2.0 and hosted in an IIS 6 server, and the OS is windows server 2003. The web application is suing a client certificate to be authenticated by a web service. We have impersonalized the application pool with de user “Network Service”. The problem is when we have to access to the private key of the certificate that is stored in the machine key/my storage. The user Network Service cannot access the key. We have given privileges to the Network Service user using the winhttpcertcfg.exe tool, however the result is the same. When we impersonalize the application pool with the local administrator the result is successfully. Therefore we think that the problem is the privileges of the user. If someone could give us some information about, we would be gratefully. Thanks in advance