This page contains both secure and nonsecure items
Sometimes creating a secure page is easy – you just change the http to https and you’re done. On other times you open the page in Internet Explorer and it starts complaining about unsecure items on the page. It’s annoying because many users get scared away thinking something wrong is going on. Or it’s just annoying since you don’t want to click ok every time you load a page.
To remove this alert follow these simple rules. After you do something reload. If there’s no more alerts you succeeded. Otherwise go on. If you get in a jam leave a comment and I’ll try to find one and add a rule.
The trick behind these is that any data that comes from an unsecure source triggers the alert. Unsecure data might come from a http:// link OR a built in page. Built in pages are for example about:blank. BUT what you wouldn’t expect is that also Explorer’s built in error pages are unsecure. So if you get a 500 or 404 error and Explorer decides to display its internal error message you will get an alert.
This might not be all but I think it should be enough.