Can I turn off impersonation just in a couple instances

Solution 1:

Make sure the Application Pool do have the proper rights that you need.

Then, when you want to revert to the application pool identity... run the following:

private WindowsImpersonationContext context = null;
public void RevertToAppPool()
{
    try
    {
        if (!WindowsIdentity.GetCurrent().IsSystem)
        {
            context = WindowsIdentity.Impersonate(System.IntPtr.Zero);
        }
    }
    catch { }
}
public void UndoImpersonation()
{
    try
    {
        if (context != null)
        {
            context.Undo();
        }
    }
    catch { }
}

Solution 2:

I am not sure if this is the preferred approach but when I wanted to do this I new'd up an instance of a WindowsIdentity and called the Impersonate method. This allows subsequent code to impersonate a different Windows user. It returns a WindowsImpersonationContext that has an Undo method which reverts the impersonation context back again.