Error code caa50021 means that the user profile was corrupted.
To resolve this issue, please follow these steps:
Open the start menu and type %userprofile%AppDataLocalTempmstmp.exe into the search box.
Right-click on mstmp.exe and choose Run As Administrator.
Click Yes to confirm that you wish to run the file.
Once completed, restart the machine.
After the reboot, log back into your PC using the same username/password combination.