I'm back again working through a PS7 Classroom in a Book text. After making changes in an image, as directed by text, cannot Save because the file is Locked. So I go to Windows Explorer and uncheck Read Only in the Properties window and then click on Apply. Then the following message appears: "An error has occurred applying attributes to the file:
D:\Lessons\lesson\04Start.psd. Access denied." I've tried every way possible to unlock the file via the Properties dialog, but can't get anywhere. Really need a suggestion.

Thanks, Len Schweitzer