Windows 10 Strangeness - everything isn't working

Question

I'm running windows 10 professional, single user account, on a Dell XPS 15 16GB RAM, 1TB SSD, less than 1 year old. Two days ago I noticed very strange, major software problems after a reboot. I can't seem to fix it. I'm actually running insider preview build 16237.rs_prerelease.170701-0549

It's all a bit odd, and I can't pinpoint the problem; it seems to be some primitive service or privilege problem?

Many apps don't launch:

• Word, Settings, Edge, Firefox, many of the new metro panels (add new user, windows update settings), regedit --> clicking on icon gives an hourglass for 2 seconds then nothing. So I have no usable web browser.
• Google chrome: blank window appears, no title or close icon, just white rectangle.
• Picture viewer: 'File system error (-2147219200)' in a dialog box.
• Some programs launch fine - Adobe Acrobat, Notepad, Paint, Explorer, device manager, msconfig (all services are enabled), taskmgr all working.
• Every 10 minutes or so, I get the "ctfmon.exe unknown hard error" message.

ctrl-alt-delete doesn't work

• first time I press it, I get "the sign in process couldn't display security and sign in options when ctrl-alt-delete was pressed. If windows doesn't respond, press esc or use the power switch to restart".
• Subsequent times, the combination does nothing.

Can't shutdown:

• Log off, and shutdown -> black screen with endless hourglass.
• switch user -> black screen with arrow mouse cursor.
• Note I have it set up so there's no login screen, goes straight to desktop.

Can't start in safe mode:

• msconfig shows "safe boot" ticked, but doesn't seem to have any effect.
• I can't get to the logout screen or to the settings, so can't use the other methods of getting to safe mode.

I don't have any bootable media here, but surely there must be a way to get to safe mode without that?

Can't get elevated prompt.

• When running cmd.exe as administrator, the whole screen goes black with hourglass cursor, unresponsive though I can move the mouse. Need to power down.
• In fact running any program as administrator gives the same problem.
• The normal command prompt works though.

Can't update (added after @spike_66 comment)

• Typing "update" in start menu gives "check for Java update", "gpupdate", "WindowsUpdateElevatedInstaller" --> black screen crash when I run that
• "View installed updates" -> hourglass 2 seconds, then nothing happens.
• "Find and fix windows update problems" -> gets stuck at "checking for pending restart"

Answer 1

The first thing to do would be to determine if it's a hardware or a software issue.
Try using a live CD, there are many free Linux ones. They usually include a memtester too.
If that works fine, I would assume it's software problem with Windows. Maybe a driver issue. Try checking the event viewer for errors.
However, with very strange system issus, it's often best to wipe and start over.

Answer 2

Long time ago now, but I didn't find a proper resolution for this.

This is the workaround I used:

• Wait for 'windows loading' indicator (rotating dots)
• Turn off power (hold power 10 seconds) whild these dots are showing, before windows starts
• Turn on and repeat this 3 times
• Windows recovery appears. Navigate through advanced options and find advanced windows startup options. Windows will restart again.
• Now you get a boot menu, and can select "safe mode with networking" (networking will not work though)
• Once into safe mode, create a new user account, with administrator privileges

(as per this solution https://www.urtech.ca/2015/09/solved-fix-windows-10-start-button-does-nothing-in-10-minutes/)

net user TempAdmin1 “password1” /add
net user TempAdmin2 “password2” /add
net localgroup administrators “TempAdmin2” /add

and transfer required files from old account to TempAdmin1 while logged in as TempAdmin2.

• restart and log into new account

The new account should function correctly. Old account still not fixable...