Microsoft.Interop.Security.AzRoles.AzAuthorizationStoreClass.Initialize fails with System.IO.FileLoadException

Our ASP.NET web application uses Authorization manager. On a page of this web application, the authorization store which is a local XML file on the server is accessed many times to perform access check. Some clients of ours are getting a System.IO.FileLoadException when they access this page. This is intermittent.

Stack trace:

System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.IO.FileLoadException: The process cannot access the file because it is being used by another process. (Exception from HRESULT: 0x80070020) at Microsoft.Interop.Security.AzRoles.AzAuthorizationStoreClass.Initialize(Int32 lFlags, String bstrPolicyURL, Object varReserved)

The process monitor shows a SHARING VIOLATION. I have searched for a solution, but could not find one. The client is on Windows Server 2003 SP2. So this hotfix http://support.microsoft.com/kb/919754 does not seem to apply because it is part of Windows Server 2003 SP2.

The code to access the authorization store is like this:

private IAzApplication2 AzmanApplication
{
    get
    {
        AzAuthorizationStoreClass store = new AzAuthorizationStoreClass();
        store.Initialize(0, _connectionString, null);
        return store.OpenApplication2(_applicationName, null);
    }
}

Anyone have any ideas how I could resolve this?

this means that file (probably the XML file you have for AzMan) is open in another application. make sure azman.mmc is not running having this store open for edit/review etc.