I recently installed a clean version of Windows 8.1 Professional on my Lenovo Y500 (with Samsung 256GB 840 Pro SSD). I have Windows all set up and running normally. I am trying to dual boot Windows 8.1 and Ubuntu 13.10, but the installation procedure don't allow me to either "Install alongside..." or shows my SSD partitions correctly when I chose the "Something Else" option. I have created a 25GB partition of free space in the Windows disk manager, but on the installation screen on Ubuntu, it shows the whole drive as a free space. I have tried installing with a burned .ISO disk and a bootable USB, the results are the same for both. Windows Disk Management screen: http://imageshack.us/a/img855/9504/59zu.jpg The Ubuntu installation screen: http://imageshack.us/a/img62/2712/9g6i.jpg I've ran into this problem before when trying to dual boot Ubuntu and Windows 7 Professional a month ago. But I gave up and never resolved the issue. --EDIT-- I tried what Eero Aaltonen suggested, and this is my result: ubuntu@ubuntu:~$ sudo parted /dev/sda print Warning: /dev/sda contains GPT signatures, indicating that it has a GPT table. However, it does not have a valid fake msdos partition table, as it should. Perhaps it was corrupted -- possibly by a program that doesn't understand GPT partition tables. Or perhaps you deleted the GPT table, and are now using an msdos partition table. Is this a GPT partition table? Yes/No? yes Model: ATA Samsung SSD 840 (scsi) Disk /dev/sda: 256GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags ubuntu@ubuntu:~$