This issue could be due to some corruption or damaged files in the Boot Sector or system partition which are required for Windows 8.1 to boot successfully. Error code 0xc0000034
First try doing an Automatic Repair using the Windows 8.1 installation/recovery media (DVD/USB disk) and check if that resolves the issue. If you do not have the Windows 8.1 installation/recovery media (DVD/USB disk), then use the power button to restart your computer during the boot process three times continuously (do not let it get to the end of the boot process). This should bring up the Windows Recovery Environment.
Once you get the Windows Recovery Environment, then try the following steps and check if that resolves the issue.
a) From the “Choose an option screen”, click on “Troubleshoot”.
b) Click “Advanced Options” in the “Troubleshoot” screen.
c) In the “Advanced Options” screen, click “Automatic Repair”.
d) Follow the on-screen instructions to complete the Automatic Repair.
Now, try booting the computer. If that doesn’t help, then you may again access the Windows Recovery Environment on the computer and then try rebuilding or repairing the Master Boot Record, Boot Sector and the Boot Configuration Data and check if that resolves the issue. You may follow these instructions:
a) Access the Windows Recovery Environment on the computer
b) Click on “Troubleshoot” and then select “Advanced Options”.
c) Click on “Command Prompt” and type the following commands and press “Enter” after each command:
d) Restart the computer and check if the issue still persists.
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