This is a great question of which I don't know the answer. On the surface it seem easy but I have a colleague who is also have difficulty figuring this out. So this project is on my plate and once I figure it out I'll update this thread. Of course you can also open up a Service Request for better tracking.
Ok I've spent some time on this now and it I've learned a few things that might help you. I'm guessing you moved the reports folder locations to the root of your D drive. ISS seems to need some type of special permission to write to a root level folder. I haven't figured out how to get around that yet but what you can do is create two nested folders and post to the second one.
Make sure the permissions for IWAM and IUSR match what is set in your old folders and you should be good to go. If I track down the Magic IIS permission I'll post it.