I had to take my rMBP to the apple store for a screen replacement, so I needed to wipe my drive. I figured it would be easier to uninstall my windows bootcamp, then reinstall OSX onto a single partition. Well like always the bootcamp uninstall failed. I go to the startup repair disk utility to verify/repair the disk. Going back onto OS X to re-attempt to remove the windows partition, and to my surprise, its already gone (there is no option to uninstall it anymore, it goes through the process of trying to install it again). So I think nothing of it, and I go back into the repair disk to erase and reinstall OS X. Repairs are done, and I got my macbook back yesterday. Going into the startup repair disk utility, I do see that I have 100GB of unallocated space (from the windows partition). So I try to expand my original partition to the full SSD space and it gives me a "cannot unmount disk error". Trying to erase the partition to add a new one gives the same error. Even trying to add a second partition to reinstall Windows on, gives me the same error. Ive gone to verify/repair the disk and still gives the error. Im currently in the process of restoring my Time Machine backup on to the 400GB partition. But does anyone know how I would go about either expanding that to the full 500GB again, or adding a second partition with this unmounting error? Thanks in advance!