IE7: ActiveX Information Bar for Ajax website without ActiveX

We're deploying to our intranet (Internet Explorer 7) an ASP.NET webapp which we created and which we know does not contain ActiveX in any way. A yellow "Information Bar" is appearing when the webapp loads in the browser, with the following message:

Your security settings do not allow websites to use ActiveX controls installed on your computer. The page may not display correctly. Click here for options...

Clicking (or开发者_StackOverflow right-clicking) on the bar gives only stock Help content. How can I learn more information about the ActiveX control IE thinks is trying to load?

How can I learn the name of the control? Or its publisher? Or its location on disk?