Upgrading from Lion to Mountain Lion: Installation Failed

I'm trying to update my early 2008 MacBook Pro from Lion to Mountain Lion.*
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I downloaded the Mountain Lion installer through the app store and proceeded with the installation process, where it it said that my laptop would restart and start the installation of Mountain Lion.*
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However, when my MBP restarted, I have been I have the prompt saying the following:
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"Install Failed
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OS X could not be installed on your computer.*
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OS X Mountain Lion couldn't be installed, because the Macintosh HD is damaged and can't be repaired.*
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Click Restart to restart your computer and try installing again. "
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Everytime I restart it starts the installation process again and repeatedly fails.*
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Please can someone advise as to what I should do? And how, if it's possible to quit the installer to carry on running OSX Lion?*
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My system was operating with no issues prior to this.*
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Hope the situation is recoverable!
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Regards.

I have held the Option key on boot and all I have are 2 options, 'OS X installer' and 'Windows'.
What do you suggest I should do?
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Is there way to quit the Moutain Lion installer so it boots up my Lion Macintosh HD?
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Thank you very much for your help.