Possible Fix for “Diagnostics troubleshooting wizard has stopped working” on Windows 10.

Here is a possible fix for when the Windows 10 Troubleshooter stops working: Check to make sure your Temp and Tmp environment variables are pointing to valid fixed drives.

[Note: Last I checked, flash drives and external USB drives did not work as a temp folder. Hopefully a future Windows 10 update will fix this oversight.]

Steps:

1. Press Windows Key + Pause/Break to bring up the "Control Panel\System and Security\System" page.
2. Select "Advanced System Settings" on the left side.
3. Select "Environment Variables" at the bottom.
4. See the "TEMP and TMP user variables"? Edit those to point to a valid folder on a fixed-drive, such as "C:\Temps".
5. Do the same for the TEMP and TMP system variables. (You'll have to scroll down to find them.)

All done! A reboot now shouldn't be required, but it might help!