iTunes Media Folder location - won't take new loacation

Hi,

I am trying to change the location in Preferences - Advanced, but every time I do it (and I've tried various different locations), the location is accepted BUT after I close iTunes and re open it, the location is being reset to the default path (C:\Users\<current user>\Music\iTunes\iTunes Media). This is really frustrating and making iTunes unusable for me as all my music is located on a different drive.

I've tried this on a different profile on the PC with the same result.