Outlook 2003 occasionally throws up error messages when a message contains a formatted signature. People who have scanned their handwritten signature or want to use a graphic are getting incongruous messages about security and ActiveX.
It appears to be a side effect of Outlook’s unusual relationship with Microsoft Word 2003. When you create a signature in Outlook and click on “Advanced Edit,” Outlook launches Microsoft Word to create a little HTML file. Unfortunately, Word does a terrible job with HTML and inserts all kinds of unnecessary codes; as security settings have changed in the last couple of years, something in those codes is generating security-related error messages.
There’s two things to try that have worked for some people. Each one requires setting up your signature from scratch, unfortunately.