Microsoft has again delayed a long-awaited update to Windows XP, citing quality concerns.

The company had planned to wrap up development this week on Windows XP Service Pack 2, but a Microsoft representative said late Wednesday that the software giant had decided that more work was needed on the update before if could be released to manufacturing.

Microsoft has been forced to push back the update's release on several occasions, most recently moving the release date from July to August Windows XP Service Pack 2, or SP2, was originally set for release in June. However, Microsoft still expects to release the update this month, the representative said.

SP2 will contain a number of new features, most of which deal with security. One new feature, for example, is a Security Center that provides a view of a PC's key protection settings. An improved firewall and other tweaks are also planned.

Among the challenges Microsoft faces is maintaining compatibility with existing software while boosting the reliability of the core operating system.

Earlier this week, Microsoft issued a warning that the newest version of its software for managing customer relations will not work with SP2. Customers using Microsoft Business Solutions CRM Sales for Outlook 1.2 will encounter problems with the software if they install the SP2, the company said.

Microsoft has posted a patch to its Web site that it says will fix the problem