CricketMX.com

Microsoft released a "critical" fix on Thursday for a security issue left unresolved by the Windows XP Service Pack 2.

The configuration change closed a hole in the Windows firewall settings that could open up PCs to attack if the machines had been set to share files or a printer with the local network...

The hole could allow anyone to access a PC that has its file sharing exceptions set up in the Windows XP SP2 firewall.

Windows XP users who use Windows update will automatically download the configuration changes.

Microsoft says its Service Pack 2 update adds an additional layer of security to Windows XP-based PCs. However, recent PCW tests seem to show that at least two major security suites are crippling SP2's ability to offer users accurate security information.

SP2, which Microsoft rolled out in August, includes the new Windows Security Center. This feature alerts users when their PC's antivirus or firewall software is missing or out of date. It also signals when the real-time virus scanner is disabled, and when the firewall is not enabled. At least, that's how it's supposed to work.