Windows 7 index locations spontaneously changing

I'm having a problem with the Windows 7 indexing service that I cannot for the life of me figure out.

I have a list of very specific locations that I like indexed. Whenever I install the OS, I always set up the indexing service to index these specific areas. The problem I'm encountering is that they don't STAY that way!!!

Every so often, I'll find that Windows has CHANGED my selections! For example, the parent folder of a folder I want indexed will be deselected, so that, when I try to search that area, I'll get the "this folder is not indexed, blah, blah, blah". And so, I'll go back into the Indexing control panel, reselect the parent folder, and go on my merry way.

The issue is, I shouldn't HAVE to re-select the parent folder!

So, how can I lock the index location selections that I've set up? How can I keep the OS from making any changes to this list, and why is it happening in the first place?!?

Thanks for any help you can give me!