I have been banging my head against the wall on this one.  I wrote an Outlook 2007 rule that was set to “run a script”.  I used the Outlook integrated Visual Basic Editor (Alt+F11) to create one that would parse an email, pull out an html link for an xml file and save this url.  But, after my machine crashed and burned one night, it just stopped working.  It was broken.  I tried everything: rebooting the machine, exiting and reopening outlook, rewriting the script from scratch, removing and re-adding the rule.  Finally I tried one last thing that actually worked:

1. Copy the script code to a notepad file. 
2. Exit Outlook.  
3. Go to %USERPROFILE%\Application Data\Microsoft\Outlook
4. Delete the file named VbaProject.OTM.  
5. Start Outlook
6. Open up the integrated Macros VB Editor 
7. Paste the Rule Procedures from the Notpad file
8. Re-edit the script
9. Viola! It works again.

What a headache!!! Hope this helps.  Check out the cool google ads!!  ;)