Hello

Since yesterday at power on, my Windows 8.1 hangs on logo screen for 2 hours 

then restarts to Diagnose Your PC for another 2 hours

then loops  back on restart to logo screen.

The same occurs in safe mode. Meanwhie I optimized the drive from another OS on the same HDD which works fine. 

My Windows 8.1 is updated automatically and used to work every day.

Have I to reinstall from scratch or is there anytool that could help to repair this?

Hi,

Could you login system now? If that it is, System Restore would be a efficient way to fix this problem. If you couldn't access to your system, you should make system repair to fix this problem.

On the other hand, this problem can be caused app which startup with system hung, then caused system problem.

Clean boot should be work to check if it is app startup with Windows problem.

http://support.microsoft.com/kb/929135

if you not able login to windows and safemode, means Windows is already corrupted

try again to go to safe mode, maybe this time you lucky

there is some step you can try, you can try to fix boot file via cmd, but you need DVD OS or backup recovery Flash drive

https://neosmart.net/wiki/fix-mbr/#Fix_the_MBR_in_Windows_8_or_81

there also another way to go to recovery environment, using 3rd party software (not free) Download Easy Recovery Essentials

https://neosmart.net/wiki/fix-mbr/#Fix_the_MBR_with_Easy_Recovery_Essentials

if still failed, the last step will be clean install

• Edited by britishdhez 22 hours 48 minutes ago

if you not able login to windows and safemode, means Windows is already corrupted

try again to go to safe mode, maybe this time you lucky

there is some step you can try, you can try to fix boot file via cmd, but you need DVD OS or backup recovery Flash drive

https://neosmart.net/wiki/fix-mbr/#Fix_the_MBR_in_Windows_8_or_81

there also another way to go to recovery environment, using 3rd party software (not free) Download Easy Recovery Essentials

https://neosmart.net/wiki/fix-mbr/#Fix_the_MBR_with_Easy_Recovery_Essentials

if still failed, the last step will be clean install

• Edited by britishdhez Thursday, April 23, 2015 8:35 AM

if you not able login to windows and safemode, means Windows is already corrupted

try again to go to safe mode, maybe this time you lucky

there is some step you can try, you can try to fix boot file via cmd, but you need DVD OS or backup recovery Flash drive

https://neosmart.net/wiki/fix-mbr/#Fix_the_MBR_in_Windows_8_or_81

there also another way to go to recovery environment, using 3rd party software (not free) Download Easy Recovery Essentials

https://neosmart.net/wiki/fix-mbr/#Fix_the_MBR_with_Easy_Recovery_Essentials

if still failed, the last step will be clean install

• Edited by britishdhez Thursday, April 23, 2015 8:35 AM

Run the Command Promt and use bootrec.exe to repair your boot issues. Check this if you need step by step guidance: 7tutorials.com/command-prompt-fix-issues-your-boot-records