I am quoting information from [http://blog.tjitjing.com/index.php/2007/03/things-i-can-and-cannot-get-to-work-in.html] because I tumbled in this issue and forgot to "just" restart Outlook :^)
Whenever I went in to Tools - Macro - Macros, selected my macro and hit run I would end up in the Visual Basic editor with an error message saying “The macros in this project are disabled. Please refer to the online help or documentation of the host application to determine how to enable macros.”
I went in to Tools - Macro - Macro Security and first changed from the default “Warnings for signed macros; all unsigned macros are disabled” to “Warnings for all macros” and finally to “No security check for macros” but I still could not get the macros to run.
In spite of a lot of Googling I found nothing. Then I realized I hadn’t tried trick no 1 in the book: Restart Outlook. And of course that was the solution.
(Note to Microsoft: Please add a “Outlook needs to be restarted” message. Note to myself: Don’t be so stupid next time around)
A good thing in Outlook 2007 is that I no longer get the “A program is trying to access e-mail addresses you have stored in Outlook. Do you want to allow this? … Allow for x minutes”. I assume they have gotten rid of this annoying message and replaced with some security feature that does not require user intervention.