Thanks Gavin. That message indicates that corruption has occurred in your user profile. We can attempt a System Restore to try and fix the issue. To start the restore, start or re-start your computer and as soon as you see the manufacturer's logo begin steadily tapping the F8 key. You should shortly see the Advanced Boot menu. Using the up/down arrow keys select Safe Mode with Command Prompt and press Enter. Enter your password XXXXX prompted.
You will get a black screen where you will see this prompt: C:\Windows\System32>
At that prompt enter: rstrui.exe and press enter. This will launch System Restore
(it may not start immediately so please give it some time)
When the System Restore window opens click Next and place a checkmark in the box labeled Show More Restore Points. Select a restore point with a date you are certain you could log in on and click Next.
Follow the prompts to start the restore. The machine will restart when the restore is complete and you should then be able to log in normally. Sometimes the first restore point will not work. If that happens perform the procedure again and choose the next oldest restore point and work your way back if needed.
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