The latest iTunes (as of March 2017) gets installed and gets pointed to C:\music on the initial install. When iTunes is started it gets the message "The folder "iTunes" is on a locked disk or you don't not have write permission for the folder". The folder is NOT read only and it HAS the right permissions. We've gone as far as to change the C:\music folder permissions to FULL for EVERYONE.
This is on a WIndows 8.1 Pro, 64-bit OS. The machine is also on a domain with redirected folders. Even so, this install should work because it is installed locally where the domain user is also the in the local administrator's group (much less giving EVERYONE the same privileges).
CHKDSK C: /F was run but there were no errors.
CHKNTFS C: was not dirty.
The system is not fragmented and the MFT only has 2 fragments.
Real answers only - no "read this blog" or "click this link" please.