One of the computers on our network ran out of harddisk space, and it turned out the size of the Windows folder is given as nearly 70Gb (when going to my computer, then the c drive) and then right clicking and selecting properties of the windows folder. However, when selecting all files and folders within that folder and right clicking and selecting properties the total size is only about 4Gb. Hidden files and folders are shown and selected while doing this. All folders are set to show hidden files and folders. Thinking the file system is borked, I did do a file system check on a restart, but the file system was found to be fine. At first offline folders where set to be used, but I did disable that and restart. What can the cause be and how do I fix this?