Microsoft plans to start pushing out Windows XP Service Pack 2 (SP2) to PCs running Windows XP Professional Edition tomorrow (25 August), after a nine-day postponement.
Microsoft had delayed automatic distribution of the mammoth service pack because it had not realised how many business customers use the Windows Automatic Updates feature for patches.
The software maker sent a note to corporate customers saying the delay was in response to customer requests for more time to install a registry key that will block the automatic delivery of SP2.
"When we designed Automatic Updates, we had consumers and small businesses in mind. We have been surprised by the number of enterprises which use Automatic Updates," said Jon Murchinson, a programme manager at Microsoft.
Faced with concerns from business users, Microsoft made a tool available that allows users to set a Windows registry key that will instruct the system to skip downloading and installing the service pack for 120 days, but still download other critical updates. The tool was released one day after the network installation package for SP2.
SP2 is more than the usual roll-up of bug fixes and updates; it makes significant changes to Windows in the name of increased security. As a result, the service pack can render existing applications inoperable.
Because of those changes, many businesses want to hold off on installing the update and are taking time for testing. Automatic Updates initially did not give users that flexibility.
Although Microsoft advises consumers to enable Automatic Updates, the company recommends businesses use patch management tools such as its Systems Management Server and Software Update Services or third-party products.
The initial schedule called for Microsoft to begin pushing out the already-delayed SP2 to all editions of Windows XP on Monday 16 August. Systems running Windows XP Home Edition finally started downloading SP2 on Wednesday 18 August.
Microsoft has labeled SP2 a "critical" update and urges all Windows XP users to install it as soon as possible. The software maker expects about 100 million PCs will be updated by October via Automatic Updates alone.
Microsoft has published several articles in its knowledge base listing more than 200 applications that may not work correctly after installing the Windows XP update.
"This is not just a patch, this is a material update to your operating system. You want to roll it out with a standardised IT control methodology," said Dwain Kinghorn, chief technology officer at software management tools supplier Altiris. "You have to look at it as a new operating system."
While users and Microsoft are busy distributing SP2, security experts and hackers are racing to be the first to find a security problem in the software. Researchers with German Heise Security in a bulletin published 13 August said they found two problems with a security feature in SP2.
Microsoft is investigating the reports, but has said it is not aware of any way for an attacker to use the flaws to gain access to a Windows machine.
Joris Evers writes for IDG News Service