Microsoft issued another <A HREF="http://www.globetechnology.com/servlet/story/RTGAM.20030724.gtflawjuly24/BNStory/Technology/">batch of security warnings</A>, including a critical flaw that affects most Windows PCs. The Globe and Mail reports that the most serious of the flaws involves DirectX, a library of graphics and multimedia programming instructions used by most PC games, and could allow malicious users to run code of their choice on a vulnerable PC.