On Friday Dec 11 2009, Office 2003 started displaying following error message when trying to open files which are protected using Rights Management System(RMS)

"Unexpected error occurred. Please try again later or contact your system administrator"

Microsoft have released patches to resolve this issue. You can get the hotfix from following locations

Office 2003 Client

Description of the Office 2003 documents protected with AD RMS/RMS Hotfix package: December 11, 2009

http://support.microsoft.com/?kbid=978551 

Word Viewer

Description of the Word Viewer documents protected with AD RMS/RMS Hotfix package: December 11, 2009

http://support.microsoft.com/?kbid=978558

Excel Viewer

Description of the Excel Viewer documents protected with AD RMS/RMS Hotfix package: December 11, 2009

http://support.microsoft.com/?kbid=978557