I've never gotten this before:

You have asked Firefox to connect
securely to signout.live.com, but we can't confirm that your connection is secure.
Normally, when you try to connect securely,
sites will present trusted identification to prove that you are
going to the right place. However, this site's identity can't be verified.



What Should I Do?

If you usually connect to
this site without problems, this error could mean that someone is
trying to impersonate the site, and you shouldn't continue.


Any ideas?

Check the time/date of your computer.

Huh? Do you mean my time/date in my task bar or somewhere else?

When I clicked on "technical details" from that page, it says this:

signout.live.com uses an invalid security certificate.

The certificate is only valid for the following names:
imp.microsoft.com , signout.live-int.com

(Error code: ssl_error_bad_cert_domain)

You could try to disable your firefox add-ons to see if any causes that problem.
Other people talk about clearing your firefox cache.
Looks like it's a fairly new bug and not much talk of actual solutions yet.

Ok Thanks.

I was going to do that this morning, when it worked fine, lol. I think it was an Outlook/MS problem that they have since corrected.