I'm sorry about the issue. This a scam; please do not follow any instruction in it. Always ignore any message (or phone call) that you do not know or that you are not expecting.
Can you please close the popup window (and/or shutdown / restart the computer), and see if you can still use the computer fine?
Please reply at the box below to continue troubleshooting. Thank you.
If needed, press and hold the Power on/off button on the computer for about 10 (to 20) seconds, then turn it back on and check.
When you are available, please reply at the box below to continue troubleshooting. Thank you.