>I have seen messages about this before, but can't find them. On some machines lo = Createobject('outlook.application') fails, even though Outlook 2010 is installed. Any tips?

Are you sure this computer didn't use Click-to-Run installation?

Createobject('outlook.application') will only work for normally installed Outlook.

http://office.microsoft.com/en-us/excel-help/click-to-run-switch-to-using-an-msi-based-office-edition-HA101850538.aspx