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* Did you try system restore to avoid this problem? If yes, proceed to the next step.
* In this regard, when you restart the computer, Tap F8 key and you would get the boot options. In that run the System repair and you can try repairing the installation, If it has already past the necessary installation of Windows 7, it would try fixing the same. If not, Vista will be repaired.
* If that didn't work, try Clean install of windows 7 instead of upgrading.
* If the issue persists, can you provide the complete system configuration? You can use this to find the system configuration.
Speccy - System Information - Free Download
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