Then, some of them may turn to Windows built-in Disk Management, thinking that they may find a solution to extend their C drive, but only disappointed to find that the menu item extend volume is grayed out (In computer programme, if a menu item is visible but not working, it is called grayed out) like shown below. In this circumstance, many users pin their hopes on cleaning up the disk fragmentation, but with little effect. With the increase of computer using time, the remaining disk space of C drive is getting smaller and smaller, leading to a slower running speed of computer.
