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macrumors 6502a
Original poster
Dec 29, 2009

I just purchaed Mountaion Lion, but I can't install it. The installer keeps saying "This disk cannot be used to startup your computer" even though I am using that disk right now. I tried making the partition smaller, like the support document said when updating from SL to Lion -- I am going from Lion to ML. I checked to see if my MacBook is supported and it is. Maybe it has something to do with my computer not having a Recovery partition (I was trying to dual boot Ubuntu [unsuccessfully] and ended up messing with a bunch of drive stuff) Can somone please help me, I'm stuck!

I am running OS X Lion on a Late 2009 White Macbook



macrumors newbie
Jul 25, 2011
Same here. MBP mid-2010. I had reEfit installed but removed before installation.
Last edited:


macrumors newbie
Dec 8, 2011
Try this...

I had the same problem earlier.. Finally, after several attempts...

1. Create a new partition (dont make it too big - i used 128gb)
2. Erase free space of that new partition (fastest is fine)
3. Reduce partition size of the original mac hd (approx 128mb.. Could be more)
4. Re-install mountain lion and it should work (hopefully)

I think you can interchange step 2 and 3.. Probably doesnt matter

Good luck!
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