This is really technical and won't be fixed with some general tips or tricks. Your Mac fails to read it that means it underwent some corruption that OS X is unable to get it. Since PC is a different platform than OS X, it somehow seems to read the disk, that too incorrectly. You must first get this disk checked with a HDD repair software. If it got a directory structure corruption then it might get fixed with the help of partition repair software such as Disk Warrior (http://www.alsoft.com/diskwarrior/). You can also try Stellar Volume Repair (http://www.stellarphoenixrecovery.com/software-volume-repair.php). Both the repair software are good choices for directory structure replacement. Though, Stellar Volume Repair is much cheaper than Disk Warrior and is equally skilful.