Could you describe the situation in more detail? Are you using Outlook mail (the new version of Hotmail) and you are getting the mixed active content block "shield" icon when viewing some pages on the site?

If it's a mail message with an embedded video, I could understand why maybe that wouldn't be secure. But I would be concerned if you see this often because it could indicate that the site is being compromised by spyware or malware on your system.

Could you try the site in Firefox's Safe Mode? That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Diagnose Firefox issues using Troubleshoot Mode.

You can restart Firefox in Safe Mode using

Help > Restart with Add-ons Disabled (Flash and other plugins still run)

In the dialog, click "Start in Safe Mode" (not Reset)

Any difference?

There has been a change in the Java security settings, see:

• http://kb.mozillazine.org/Java#Java_security_prompts

• "What should I do when I see a security prompt from Java?":
  http://www.java.com/en/download/help/appsecuritydialogs.xml

If you visit a website regularly then a possible workaround is to add the URL to the Java Exceptions Site List, see:

• "Why are Java applications blocked by your security settings?":
  http://www.java.com/en/download/help/java_blocked.xml
• "How can I configure the Exception Site List?":
  http://www.java.com/en/download/faq/exception_sitelist.xml