Looks like you've figured it out, but here's a few other tidbits on hidden files:
1. While system files are one type of hidden file, any other file/folder can be designated as hidden, too.
2. This is not a recent feature, it goes back to Windows 95 at least, I believe even DOS.
3. The default behavior in Windows is not to show hidden files. This has also been the default for as long as I can remember. It's possible for this to be customized by the manufacturer prior to or during installing the OS but I've never seen an installation "in the wild" that did this.
On your old machine, either the manufacturer did some unusual (but helpful) customization, or it was changed manually at some point to show hidden files.
As for why the folders were hidden in the first place - maybe Sansa wants you to use their own utility for uploading music? Just guesswork here, I've never used a Sansa player.
1. While system files are one type of hidden file, any other file/folder can be designated as hidden, too.
2. This is not a recent feature, it goes back to Windows 95 at least, I believe even DOS.
3. The default behavior in Windows is not to show hidden files. This has also been the default for as long as I can remember. It's possible for this to be customized by the manufacturer prior to or during installing the OS but I've never seen an installation "in the wild" that did this.
On your old machine, either the manufacturer did some unusual (but helpful) customization, or it was changed manually at some point to show hidden files.
As for why the folders were hidden in the first place - maybe Sansa wants you to use their own utility for uploading music? Just guesswork here, I've never used a Sansa player.