I installed the update KB2919394 and my computer was thrown into the dreaded automatic repair loop, which Microsoft hasn't fixed yet.
Anyways I thought I would give some solutions on how to get out of this. Solution 1 is what worked for me.
Solution 1
This solution is to disable the automatic repair from starting if your computer fails to boot into windows.
What you will need - A Windows 8 or 8.1 CD
Step 1: Place the CD in your drive and proceed to boot from it
Step 2: When the install screen pops up, look to the bottom left and select "Repair Your Computer".
Step 3: You will now see a screen that says "Choose an option". Select "Troubleshoot", then "Advanced Options", and finally "Command Prompt".
Step 4: You should now see the command prompt. Type "bcdedit" (without quotes) and hit enter.
Step 5: A list should have appeared. Towards the top, you should see "resumeobject" (It is under "default"). Highlight the long number, including the brackets, and copy.
Step 6: Now type "bcdedit /set (the long number you copied) recoveryenabled No" (Without quotes). Hit enter.
Step 7: You should now see the message "The operation completed successfully"
Step 8: Type "Exit" (Without quotes)
Step 9: Reboot
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Solution 2
Booting into safe mode first, then rebooting the computer.
What you will need - nothing
So you are at the screen that says something on the lines of "Windows did not load properly".
Step 1: Select "Advanced repair options"
Step 2: Select "Troubleshoot"
Step 3: Select "Advanced Options"
Step 4: Select "Start up settings"
Step 5: Select "Restart"
Step 6: The computer should restart. Now you want to hit the 4 key, which is safe mode.
Step 7: You should be able to log in now. Restart the computer and the computer should boot normally.
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Solution 3
Running check disk to see if your hard drive is the problem
What you will need - A Windows 8 or 8.1 CD
Step 1: Place the CD in your drive and proceed to boot from it
Step 2: When the install screen pops up, look to the bottom left and select "Repair Your Computer".
Step 3: You will now see a screen that says "Choose an option". Select "Troubleshoot", then "Advanced Options", and finally "Command Prompt".
Step 4: Type "chkdsk /r C:" (Without quotes)
Step 5: The scan should start. This could take several hours depending on the size of your hard drive.
Step 6: Once the scan is done, type "exit" (without quotes).
Step 7: Reboot
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Solution 4 (Found out by user DayDay13)
Making sure your hard drive is first in boot priority.
What you will need - nothing
Step 1: Boot into BIOS on your computer
Step 2: Go into your boot priority list
Step 3: If you see "Windows Boot Manager" as number 1 in your priority, change it so that your hard drive is number 1.
Step 4: Save and exit BIOS
Step 5: Reboot
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Microsoft community, please do not delete this thread. These are confirmed solutions that have worked for many others with the automatic repair loop problem. I will add more if any other solutions become available.