boot loop

after windows update the laptop is in loop showing restoring previous version of windows.going into recovering mode f4 then trying to recover to previous saved setting i get a box saying enter server authentication key.what's this.

samsung 770z chronos

 

Unfortunately Samsung Recovery Solution (=SRS, F4) is not very resilient, and easily disturbed. Updating Windows to a new version almost always breaks it.

Depending on how much damage the Windows Update has done to the partition layout, re-installing the original Windows version usually makes SRS work again. So if your laptop came with Win7 originally, installing Win7 from DVD onto the Windows partition will probably allow you to load SRS with F4. Similarly if it came with Win8.

Our Samsung Forum Sticky List has links to clean install guides for both Win7 and Win8. Note that you don't have to install drivers etc if your only goal is to make SRS work again. SImply installing the original Windows version onto the Windows partition is usually enough.

Of course this will wipe the contents of the Windows partition and start you over (or restore to a restore point if you made backups in SRS).

Another question is what caused the computer to boot loop after the Windows update, and whether that can be resolved. To diagnose that will require more info, including your exact model number, which Windows version you were updating from and to, and whether you are running in UEFI or legacy BIOS mode (if you have that information).