I have seen this in a few rare cases after a reboot, where all folders and files will have the Read Only Attribute. If you uncheck it, it will just come back. It is more of a filesystem issue in Windows than a configuration issue and it looks like when Windows detects a badly corrupted filesystem that it will make things read-only, sort of like Linux would.
If you are Administrator or the owner of the folder and this is happening it is probably due to the reasoning mention........