"There was a problem sending the command to the program" error in Excel

Microsoft Excel 2007
1.Click the Microsoft Office Button, and then click Excel Options.
2.Click Advanced, and then clear the Ignore other applications that use Dynamic Data Exchange (DDE) check box in the General area.
3.Click OK.


Microsoft Excel 2003 or earlier versions of Excel
1.On the Tools menu, click Options.
2.Click the General tab.
3.Clear the Ignore other applications that use Dynamic Data Exchange (DDE) check box, and then click OK.

E-Mail address autocomplete on windows 7

The Outlook autocomplete file can be found at C:\Users\abc\AppData\Roaming\Microsoft\Outlook, where abc is your username.  The file will be named the same as the default Outlook profile with .NK2 for the extension.