Facebook users were told "This link has been reported as abusive" on Thursday when they attempted to access the NBC.com website.
Several security bloggers warned on Thursday that the site was infected with malicious software, advising computer users to avoid the site.
Officials with NBC could not immediately be reached for comment.
(This story is corrected with changes in paragraph 3 to Thursday from Tuesday)
(Reporting By Jim Finkle and Jennifer Saba; Editing by Gary Hill)