Many applications and files run alongside Microsoft office software. The .MSI files are the database of all the settings, files and configuration information for the related application. One of these files is Pro11.MSI which allows you to customize anything associated to office software. This file incorporates security and language settings, installation sources and the setup process. If you do not have the installation DVD for MS Office and unable to update Pro11.MSI file, you can manually create an XLStart file. Open Windows Explorer and locate the folder which contains the installation of Microsoft Office 2000, Office 2003 or Office XP. Select the version of Office that you are running, create a new folder and rename it as XLStart and close Windows Explorer. Restart your system and launch the Excel application.