In an extremely small number of cases users have reported that music files saved on their computer were removed without their permission. We’re taking these reports seriously as we know how important music is to our customers and our teams are focused on identifying the cause. We have not been able to reproduce this issue, however, we’re releasing an update to iTunes early next week which includes additional safeguards. If a user experiences this issue they should contact AppleCare.

Source: Apple says it doesn’t know why iTunes users are losing their music files | The Verge

oops