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I first installed Windows 7 ultimate onto my machine and using Windows 7 built-in partitioning system, I partitioned my disk into many smaller disks of NTFS file systems. I then tried to install Ubuntu 12.04 onto my machine.

I installed Ubuntu and Windows 7 side by side because I needed both operating systems but while booting I was getting an error:

Attention out of range
H:92.6KHz  V:58.2Hz

I was not getting any dual boot menu - no message was seen except the above message. I tried pressing the down arrow to move between meu items, thinking that the menu might be there just not shown. The first time it directly logged into Ubuntu then next time Windows 7.

When I logged into Windows 7, I deleted the volume in which Ubuntu was installed. Now, I am getting this error:

error:unknown file system 
grub rescue>

I want Windows 7 back and a better way to install both operating systems. Please give me some help in this regards.

marked as duplicate by karel, Zanna, Fabby, NickTux, Eric Carvalho Nov 15 '18 at 17:47

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.


If you have a Windows CD you boot your PC from it and you go to Repair. There you will see the option to open the CMD.

In cmd you type this 2 codes:

bootrec.exe /FixBoot
bootrec.exe /FixMbr

And you will get your Windows boot back. After that just try reinstalling Ubuntu as usual and it should work.

  • after trying this two commands i got an error as A disk read error occured to (some unidentified ascii characters) – A palekar Jul 26 '12 at 16:07

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