If your phone or PC is interrupted with a flashing message that appears to be from Microsoft Security Services saying there is suspicious activity on your account or your device has been infected, then list a telephone for you to call for help, DO NOT do so. This is because the message is a scam being used to trick potential victims into calling call centers operated by scammers. The scammers will pretend to be from Microsoft and ask callers to disclose their account credentials, personal and financial information.
Once the scammers received their potential victims' information, they will use it fraudulently. Therefore, if you have been tricked by the Microsoft Security Alert scam message into disclosing your banking information, please contact your bank for help. Also, try changing your account passwords.
The Microsoft Security Alert Scam Popup

Remember, Microsoft will never ask you to call them if their antivirus software detects something suspicious on your computer or if it is infected with malware. Therefore, if you see a message with appears to be from Microsoft asking you to call a telephone number listed in the message, it is a scam and should not follow the instructions in it.