If receiving an error for extend.dat when starting Microsoft Outlook. This file caches the registry files for Outlook for 3rd party applications such as extra buttons in Outlook and so on. If you rename this file (extend.OLD) it will force Outlook to search the registry for Outlook entries and will create a new extend.dat file.
Located:
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Microsoft\Outlook
If you can't see it make sure you have selected "Show hidden Files and Folders in Tools > Folder Options > View
Once you've found extend.dat rename it to extend.OLD
Then try opening Outlook again.
If this problem still occurs try moving extend.dat into:
C:\Documents and Settings\All Users\Shared Documents\
Then try outlook again.
This should be working ok now.
Located:
C:\Documents and Settings\%USERNAME%\Local Settings\Application Data\Microsoft\Outlook
If you can't see it make sure you have selected "Show hidden Files and Folders in Tools > Folder Options > View
Once you've found extend.dat rename it to extend.OLD
Then try opening Outlook again.
If this problem still occurs try moving extend.dat into:
C:\Documents and Settings\All Users\Shared Documents\
Then try outlook again.
This should be working ok now.
