ITunes has stopped remembering where my library is

Question

I am using Windows 8 and iTunes 11, whatever the latest version is.
My music library is F:/MyMusic/iTunes/iTunes Music. Everything is in the iTunes folder: the music files, the iTunes library files, etc. You can tell because the folder is "iTunes Music" that it was created a while ago, before it was changed to "iTunes Media" or whatever it is now. Anyway, I have never kept multiple libraries, or split my libraries, or anything. iTunes had no problem recognizing this setup or accepting that my library wasn't on the C drive until a couple of days ago. I've had it this way since I got my present computer a few months ago and put the library folder on it. I didn't have any problems then with getting iTunes to run the library from the F drive. Remember, nothing has ever been on the C drive.
Here's what happened: my iPod was dead. It is from 2006, so it's quite old and loses its charge fast now. Anyway, I plugged it in and got the message on it that says the battery is low. Same as always. Usually when it gets enough juice the computer recognizes the device, iTunes launches, it syncs and all the other stuff that is supposed to happen happens. This time, though, the iPod seemed to get stuck a couple of times. The screen would flash but then the low battery message would come back. After this happened a couple of times I unplugged the iPod. Then I replugged the iPod. This time it connected but when iTunes launched I got the license message. I hit ACCEPT and it opened up without any media at all. No music, nothing. It was as if iTunes was launching for the first time. My first thought was that my library had somehow been erased. That turned out not to be true. What had happened was that iTunes for some reason had created a new library in the default location in Windows 8 - C:\Users\Username\Music\iTunes. It had never done this before and I'm not sure why it started doing that now. The hiccup with the iPod my have been simply a coincidence, though I don't think so.
I found the original library on F where it always was and it was intact; iTunes had simply forgotten where it was. The problem is that even though I use the various tricks to get iTunes to recognize it, it keeps forgetting it. That includes changing the directory location in preferences and using the Shift+iTunes command to select a library manually. SHIFT+iTunes works for a little bit, but eventually iTunes forgets and reverts to the default library it has created on C. Sometimes it even forgets the C location and when I launch iTunes it throws the license at me. I have tried deleted both libraries, uninstalling iTunes, etc. etc. etc. Nothing has helped. No matter how often I tell iTunes to use the correct library on F, it insists on reverting to the default library on C, which it keeps recreating if I delete it. And as mentioned, sometimes it forgets it has created it, since half the time the license pops up as though I were using iTunes for the first time. Even when I open the F library, it throws the stupid tutorials at me, as though I'd never used it before.
I am at my wit's end trying to solve this. It may be something complicated, it may be something simple. But I have no idea what it is. iTunes was working fine and now has become utterly useless. Something has gone wrong. Any help solving it would be appreciated. I apologize writing a lot, but I thought I should be as detailed as possible. Thanks.

Answer 1

See the thread Why does iTunes delete my itunesprefs.xml? It doesn't seem to affect every McAfee user, and it seemed to get fixed, then came back again. iTunes routinely updates certain files by creating a new .tmp version, deleting the original, then renaming the .tmp copy. For one reason or another McAfee has been causing problems with the preferences file for some users over recent months, AVG with the main .itl file. In neither case does excluding the relevant file location seem to help prevent the problem. Try disabling McAfee as test.  I'd still recommend ditching it for MSE.
tt2