When I try to publish an InfoPath 2007 form, I get the following message:
To use this feature, Microsoft Office 2007 must be set as the default e-mail program.
However, Outlook is configured as default e-mail program already. Any ideas?

I verified that Microsoft Outlook is the default e-mail program in two ways:
- I went to Control Panel > Internet Settings -> ... -> Default Programs
- I tried and entered mailto:myown-e-mail-address in Firefox and it opened Outlook.