* Critical Error * Start Menu and Cortana aren't working.

Same here.  I did an upgrade from 8.1 and I get this error.  I can't even create a new account.  Seems most programs won't work either. 

Same here..., I upgraded from Windows 7 and I am using an ASUS X553M... I can create new accounts, but to no avail, also I did a scan and found no problems on the disk.

Some software is also not working (Waterfox for example) and some of the native Microsoft Applications too...

Some help would be most welcome...

I upgraded my system yesterday and it was working well until an hour ago...

I decided to restart my system and after that, the problem occurred to me as well

Please help. I need it to be fixed as soon as possible.

Same problem here. It seems like my pc is also not responding to any keyboard shortcuts. Was planning to revert back to 8.1 but only then I found out that the setting is not working as well!!! Help please!!! I don't want to get stuck like this!

My wife had the same problem with her Toshiba after one day working good.  Followed screen prompts with same results, shut down, same results, tried 3 more times (slow to learn I guess) then tried F8-Safe mode which did not look like it was responding but after next restart - Start and Cortana returned.

I have same problem.  I have to creat new user to use it. I hope this problem will be fix as soon as.

A WORKING SOLUTION FOR ME:  After a very successful first day with Windows 10, I went to start menu last night and it did not respond.  I left clicked and a men did pop up giving me an option to shut down.  This morning on start up I see the critical error that Start Menue and Cortana aren't working.  Restart for a repair.   I restarted 3 times and continued to get the same critical error message....you don't have any access to the desktop other than a restart.  This last time I restarted I hit F8 and did not think it did anything because Safe Mode did not come on, BUT the problem appears to be repaired for now.

Hey Ty (and others),

We've fixed many of the underlying causes for this issue, but there are still some eluding us, and I'm sorry to hear that this is impacting you guys. We have telemetry and crash reports that we're watching for this, but it always helps when we hear from you guys directly in case there are extra details that might help

If you're seeing this repeatedly, we have some questions that might help us get to the bottom of this faster (there are a lot, but sometimes the smallest detail can be significant):

Setup Info

• What is your hardware setup?

• Which build are you currently on? (we'd assume the release version, but just in case 😊)

• How did you install this version? (media creation tool, windows update, etc)

• Was this an upgrade?

• If so, which build/version of windows did you upgrade from?

• Have you installed all the recommended updates from windows update?
• Did you do a system reset or use a restore point at any point? (just checking, not saying that you should!)
• Are you running safe mode or diagnostic start up? 

Account Info

• What accounts do you have on your device?
• Are they local, Microsoft Accounts (email addressed) or domain? 
• Are they admins, standard accounts, or children accounts? 
• If you upgraded, which was the account that drove the upgrade? 
• Did you connect a Microsoft account (email address) (as soon as you installed when you were prompted in the initial setup, or later in Settings?  

Error Info

• What is the specific critical error text you're seeing?  
• Did the issue go away if you follow the guidance in the dialog, or does it come up again?
• When you see the error text, can you still launch win32 applications? (try WIN+R and entering "notepad")  
• If you open task manager when you see the critical error dialog appear (press CTRL+Shift+Esc), do you see sihost.exe running in the details tab? 
• From CMD prompt, what is the output of "reg query HKEY_LOCAL_MACHINE\Software\Microsoft\IdentityStore\Providers\{D7F9888F-E3FC-49b0-9EA6-A85B5F392A4F}"? (without the quotes - you should be able to copy this, then press CTRL+Shift+Esc to launch task manager, and File>"Run New Task" and enter "cmd". When the command prompt window appears, right click on it and select paste and press enter)

Extra Info

• Do you any remember any specific details leading up to the first time that you saw this? 

Thanks again for your help and your patience,

J

EDIT: Updated to clarify acronyms :)

EDIT2: Added another piece of information the team is interested in

I'll try the feedback option when I get home.  It does seem that anything on the toolbar doesn't work but if I search the c drive for the actually file I can get it to work.  Also I keep trying to run things as an admin but it won't let me do that.  

I am using a Dell XPS18 and upgraded from 8.1

Having restarted 4 times I continued to receive the critical error start message.

I then followed the advice of "SkipinDallas", above and continually pressed the F8 key whilst restarting. As said, nothing appeared to happen until I looked back in and Cortana and the Start menu were working!