My father got this message from in his Facebook account page:
It looks like your computer is being affected by malware. We’ll help you fix the problem to keep your account secure and prevent malware from spreading to friends.
Malware is software that tries to steal personal information and causes problems when you use Facebook. Clicking or sharing links that contain spam can give your computer malware.
And I helped him to use TREND MICRO (Malware Removal) and now he can use his Facebook account again.