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Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

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  #1  
Old 25-01-2012
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Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro
  

Hi, I have dual boot MacBook Pro with OS X 10.6 and windows 7, when I added a third boot partition of Ubuntu to my existing computer using a grub it seems to have damaged my windows 7 boot and it is not working now! I have rEFIT boot partition selector screen but I am not able to enter in to the windows 7 when I click on it!When I try to go in to the windows 7 with rEFIT or by holding the OPT button at startup it returns me to the Grub selector again from where I had selected the windows 7 option after clicking on which I find nothing ahead and it only gives blank!i have read some cases like this where users have installed the grub into the windows 7 partition but this doesn?t look like my problem here? Repairing Windows 7 doesn?t seem to be helping me, can you please tell me what to do now ?

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  #2  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

The problem with your system is that when you re-repartitioned with your system for installing Ubuntu you might have replaced the windows by the Ubuntu system and because of that windows 7 is not shown in the Hybrid MBR! Now follow these steps:
  1. Download GPT fdisk for OSx or Linux version
  2. Install the GPT fdisk , after that go to terminal, for ubuntu type this: sudo gdisk /dev/sda and for mac OSX type this: sudo gdisk /dev/disk0 , this will launch the gdisk.
  3. Now type ?p? to view the partition table, keep in mind that OS X?s utility doesn?t show the EFI system partition. If table looks wrong then type the ?q? to Exit.
  4. You can have recovery by typing the ?r?, it will take you to the recovery and transformation menu.
  5. Now type ?h? to create the new Hybrid MBR. You will need to type up to 3 partition numbers. You can type ?5 6? or ?6 5? for windows and shared data partitions. You will be asked for more information, put 0xEE partition first in the table And then change the type code to ?0c? and select ?y? to tell it to put Windows partition's boot/active flag. Don?t make any second partition for now!
  6. When you are done you will again see gdisk prompt , type ?o? to view the MBR partition from table, it will have windows and shared data partitions included! if this doesn?t look right then type ?h? to create again or type ?q? to quit. Type ?w? to save the changes!
  7. Windows will boot now but if it doesn?t then go to Grub and see if you can do it from there!
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  #3  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

Well what if I had installed ubuntu fist and then windows and not ubuntu over the windows operating system? Would that be easier to me then this as this seems to be very uninteresting to me but still I will try this as I want my windows back!
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  #4  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

No, that would have been more trouble to you wiping out the part of the Grub installed on the MBR! Hybrid MBR can hold only three partitions and tools used for making hybrid MBR blindly include the first 3 partitions available on the disk! You had installed the OSX and Linux first which understand the GPt so they don’t need space in the hybrid MBR but since they were installed earlier than windows they took the space and now there is no space foe windows OS.
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  #5  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

Thanks for that! Can you tell me why Mac?s default drive selector shows the windows partition as an option if it is not going to boot while selected! Is it something like MBR directing it wrongly while making selection? Why windows fails to boot when selected from GRUB menu? What if I erase all the ubuntu and windows entirely and install the fresh copy of windows again, will it make my windows work properly? Or I would still have to make settings with MBR?
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  #6  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

I am not sure about the Mac?s built-in boot selector but I can say that when it scans for the GPT partitions, it finds the windows and offers you without checking its entry in MBR and thus windows fails to boot when you select it! Windows failing to load from Grub , is not Grub?s fault but windows! Microsoft doesn?t allow their OSs to boot on GPT from BIOS based computers it also doesn?t support version of EFI that Apple uses! To boot windows in Mac , apple has used Bios emulation layer in EFI, because of which Mac looks like bios based computer! Windows unlike the OSX and Linux it gives the side precedence to the GPT, when windows sees the hybrid MBR. Windows doesn?t even know that other partitions exists other than what it sees. Therefore windows can?t boot since it doesn?t see its own boot partition!
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  #7  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

Hey this has worked for me! at first I thought it has gone same way when it threw me on the grub but later selecting on the windows option allowed me to enter in to the windows and now I can use it actually! I have left the windows partition?s hex code and changed the shared Fat partition code to the ?0c?!
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  #8  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

You should only have changed code for the FAT?s partition! The value of the NTFS would be ?0x07?. I think that you are having some problem with rEFIT as it is not working properly. You can go to the rEFIT configuration and find some way to get it working as I don?t have enough knowledge about the rEFIT!
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  #9  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

I want to clarify and rEFIT still shows all of three operating systems! When I select the Apple icon I can get in to the apple operating system directly but if select the other operating system like ubuntu and the windows then it shows the Grub menu first and where I have to select the operating system in order to use it! it only shows single “grub” option for both windows and ubuntu!
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  #10  
Old 25-01-2012
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re: Windows 7 boot messed up by grub after installing ubuntu with rEFIt on MacBook pro

It looks like the grub is installed onto the MBR and overwritten the windows boot loader. Now rEFIT is just opting the MBR and not the boot partition for getting the boot code! When it locates the MBR it presumes it as windows code and gives you the menu for launching the windows which in turn launches Grub! You can get it worked by re-installing the Grub to the Linux root (/) or if you have boot partition then /boot partition. You can use the windows utility to re-install the boot loader in MBR. It can be risky as it can damage the boot options for other operating systems but you can decide depending on your priorities!
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