Microsoft tonight warned about a serious flaw in almost every version of its popular Windows software that could allow hackers to seize control of a person’s computer when victims read e-mails or visit Web sites.

RECENT versions of the Microsoft Windows computer operating system contain a “critical” security hole that an attacker could use to prevent some on-line transactions.

Recent versions of the Microsoft Windows computer operating system contain a “critical” security hole that an attacker could use to prevent some on-line transactions.

A US Government-backed research group is issuing a warning about a major internet security flaw.