Microsoft released a fix for a bug that temporarily locked users out of Office 2003 documents protected by the company's Rights Management Services technology.

"The issue of the inability to open Office 2003 documents protected with RMS has now been resolved with a hotfix," Microsoft's Office Sustained Engineering team said, in a blog post Saturday.

Microsoft made the patch available as a download from its technical support site.

The bug hit all components of the Office 2003 suite, including Word documents, Outlook e-mails, Excel spreadsheets, and PowerPoint presentations. Files that were not protected with RMS were unaffected by the glitch.

Users who tried to open impacted files were greeted with the following error message that said, "Unexpected error occurred. Please try again later or contact your system administrator."

Microsoft blamed the problem on the expiration of an Information Rights Management certificate.

The situation could have caused headaches for law firms, healthcare companies, government agencies, and other organizations that use RMS to impose a chain of custody over sensitive files.

The OSE team warned users about the problem late Friday.

"Starting on December 11, 2009, customers using Office 2003 will not be able to open Office 2003 documents protected with the Rights Management Service (RMS) or save Office 2003 documents protected with RMS," OSE said in its initial blog post about the bug.

Microsoft can ill afford to alienate Word customers, as the software package is facing a bevy of new free, or low-cost, competitive offerings from Microsoft rivals like Google and IBM.

Many corporate users are willing to pay a premium for advanced features like RMS, but if the technology doesn't work or becomes bug prone that willingness could quickly evaporate.

Sales of Microsoft Office and related products were off 11% in Microsoft's most recent fiscal quarter.

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