Microsoft has revealed there are "critical" security flaws in several of its software programs.
The company says that "critical" flaws in Internet Explorer 5.01, 5.5 and 6.0 could allow attackers to access and run unauthorized commands on users' computers.
In addition, the company says "moderate" flaws in several of Microsoft's business software programs - including Windows XP Professional and Microsoft Windows NT 4.0 - could allow attackers to purposely crash a computer system.
Users can download fixes from the company's website.
