http://blogs.msdn.com/doronh/archive/2008/03/17/returning-failure-from-driverentry.aspxOne thing that is easily overlooked about implementing DriverEntry is that upon return !NT_SUCCESS, DriverUnload is not called. I mentioned this anecdotally in a previous post , but it is worth expanding on. I was bit by this oversight when I was workingenCommunityServer 2.1 SP1 (Build: 61025.2)