Microsoft has acknowledged that it postponed the release of Windows XP Service Pack 3 (SP3) because the upgrade includes changes to the operating system that can corrupt data in the company's retail point-of-sale (POS) software system. In addition, Microsoft has stopped automatic distribution of Windows Vista SP1 for the same reason.

Earlier in the week, Microsoft  said its delay in releasing the web version of XP SP3 was due to a "compatibility issue" between XP SP3 and Microsoft's Dynamics Retail Management System (RMS), a POS and store-management application targeted to small- and medium-sized businesses (SMBs). It did not provide specific information about the issue then, however.

In reality, a Microsoft employee had provided details related to the issue in a post to the RMS support forum on April 24. "The Microsoft Dynamics Retail Management System (RMS) development team has identified problems when Windows Vista SP1 is installed," wrote Tom Berger, a Microsoft online support engineer, in a post available here.

Windows Vista SP1 alters the manner in which Microsoft's SQL Server database product handles database records that include information from multiple tables, Berger added in his post. "All users who have applied Windows Vista SP1 will be affected."

Microsoft has also said that users running RMS on XP SP3 would face the same problem. Hence, the delay in releasing that upgrade, as well.

Until Microsoft releases a solution to the problem, Berger wrote that the company strongly recommends that RMS users should not install Windows Vista SP1. “If you have already installed it, you can uninstall it,” he added.

A fix for the data-corruption problem is currently in testing and will be available as soon as that process is complete, a Microsoft spokesman told SCMagazineUS.com. The spokesman said the company "does not have further information to share" on the data corruption problem.

"We plan to put filtering in place shortly to prevent Windows Update from offering Windows XP SP3 to Microsoft Dynamics RMS customers," the spokesman added. "Once this is in place, we plan to release Windows XP SP3 to the web."