Avast today updated its definitions and introduced a false positive that labeled legitimate, and non-malicious, sites as infected with the the HTML:Script-inf threat. This would cause pages not to load properly while Avast issued warnings. Some of the sites affected by this false positive include Wikipedia, Yahoo, PCWorld, and Youtube.
Reports indicate that the culprit are the Avast definitions numbered 110411-1. A later update, 110411-2, appears to have resolved this false positive. So if you are receiving the HTML:Script-Inf alerts, please update your Avast in order to resolve this issue.