I'm a novice, just got a 320 gigabyte external hard drive to store my music on. I then just copied the "my music" folder on my laptop on to it, which may not have been the correct way to do it, but... Anyway, it's all on there, but I'm not able to play some of the files on Windows media player now... message reads "WMP cannot access the file. The file might be in use, you might not have access to the computer where the files are stored, or your proxy settings might not be correct." Can anyone help?

Try them with a different media player --for example
IrfanView - Official Homepage - one of the most popular viewers worldwide
Make sure you get the plug ins though.
With that program you can view video`s , listen to most music formats, and also work with pictures.
Its open source, thus free, -- though your support would be good if it works for you.
No fancy visualizations though just a basic player

Are any of these files protected? I think there are some places that only allow the file to be usable on 1 computer.

Make sure you didn't copy just shortcuts for the offending files.

Make sure the transfer is complete before trying to open any of them.

Do yourself a favor, and get VLC player. Plays everything.

Thanks very much, tried a few different media players now, and those mp3's ain't for being played. I'll download them again, and be a bit more careful. Some computer newbies are afraid of touching the machine, I'm afraid the opposite is true in my case. Imagine a monkey on a motorbike. Thanks again.