Yaswanth Ravella

Today out of the blue, when loading office 2003 on an xp machine, an error message appeared with the text:

“An extension failed to initialize. Can’t open file: extend.dat. The file may not exist, you may not have permission to open it, or it may be open in another program. Right-click the folder that contains the file, and then click Properties to check your permissions for the folder. You don’t have appropriate permissions to perform this operation.”

Being me an administrator it seemed more complicated than a permission problem. What is the extend.dat file? It is a file used to cache extensions built for outlook. The problem with the file could be fixed by either deleting it or renaming it.

If hidden files and folders are not visible you will have to set your explorer window to view those types of files. If you know how to show hidden files skip “Viewing Hidden Files”.

Viewing Hidden Files: To view folders and files that are hidden, from my computer, click tools and then folder options. Click the view tab at the top of the window. Scroll down to the option Hidden files and folders. Click the option that says show hidden files and folders. Then click OK.

The Fix: Make sure outlook is closed and not running. If you are viewing hidden files and folders, use windows explorer to go to documents and settings, then the folder of the user with the error. Next click Local Settings, then Application Data, then Microsoft, and finally click and go into the outlook folder. There is where you will find extend.dat. Now from here rename the file from extend.dat to extendOld. Restart outlook and send someone an email.

Tip : To do this in my style just type the below line at your command prompt but make sure you close outlook first

del “%userprofile%\local settings\application data\microsoft\outlook\extend.dat”