Nah, the file system of the Sansa is subject to the whims of Microsoft, just as any memory device. Having “no permission” is a generic fault message you may see when a folder isn’t quite kosher from the computer’s standpoint.
I have cured issues like this by using chkdsk on the device (you must connect in MSC mode for access), regardless of whether MSC or MTP was used for transfer of files. In the latest Windows versions, the “mouseketeer” version of chkdsk is found under Properties > Tools tab> Check Volume For Errors.
I have tried deleting the troublesome folder before, and this does also work.
After deleting the folder, you’ll find that the Sansa will “Refresh Database” opon disconnect, and will build a new default folder structure, just like a lizard growing a new tail.
The “nuclear option” always works, simply format the device, which clears everything, Note that this last resort also blotzes all of your music from the device too, so be sure to have backup copies of your music to reload after formatting.
Use FAT for 2GB or less (memory capacity of your device), or FAT32 for all larger capacities. Better yet, it’s always best to use the Format command on the Sansa itself, found under System settings.