right click on the main folder everything is stored in, select properties and then click on the security tab. Then click on the advanced button at the bottom
on the next page (advanced security settings) click on add and type everyone in the box, click on check name and it should underline it, then click ok
on the next window that comes up put a tick under allow next to full control (which should automatically put a tick in all other options) and click OK again.
now your back to the advanced security settings again, make sure there is a tick in "Replace permission entries on all child objects.." and click on OK (this may take a little while now depending on the size of your music collection)
when it's finished try copying again