Brian Durfy wrote:

I had the same problem when upgrading to Vista and Office 2007.
Unfortunately the fixes listed in this thread did not work for me. I
could never find the Extend.dat file. I struggled with this for a
few months until I came across another fix on the internet. Can't
remember where.

Open Windows Explorer and enter the following in the Address bar:

%UserProfile%\Local Settings\Application Data\Microsoft\Outlook

Click Go. You should see the file in the Explorer window that opens.

Anyways it worked for me and was actually quite simple. In Outlook
2007 follow these procedures, starting with the Tools Menu.

ToolsTrust Center
Select Add-ins from the left side menu
At the very bottom of the page there is a task bar labeled Manage:
In the task bar scroll to Exchange Client Extensions, then select the
GO button to the right.
The Add-in Manager should appear and you should see some sort of Fax
option, with a couple of other items above or below it.
Un-check the fax item and select OK.

The approach of deleting the extend.dat file works when the add-in doesn't
show in the Add-ins.
--
Brian Tillman