So I’ve had this problem with Windows Live Messenger since it’s release.
In WLM 2011 (version 15.4) they introduced a new feature that integrates with Facebook, which I
initially didn’t like, but now I like it! Only problem was that the feature that shows Facebook galleries within WLM always failed on access with Error code: 0x80042f0f after it comes up with “Loading album via Facebook”

After many months of it bugging me, I sorta gave up. Until now.
Whilst on holiday in South Australia, I noticed that my laptop did not exhibit the same problem (though I had tried it at home).
So obviously it was a problem with my internet connection (I used mobile broadband on holiday).
Today, I ran a Wireshark on my LAN connection when the error comes up and I managed to find the conversation and found some interesting information. Apparently the return page from that error was actually a HTML Error 417; a quick Google got me to this page

Simply put, Windows Live Messenger is asking for a specific header response. Apparently my Squid proxy (on my IPFire box) isn’t playing nice. WLM wants confirmation (Expect 100-continue), but Squid instead sends out an error message, and thus WLM doesn’t get what it expects and fails.

So to fix it, we need to put

 ignore_expect_100 on

In the squid.conf file (‘/var/ipfire/proxy’ in IPFire)

Although you should really put it in ‘/var/ipfire/proxy/advanced/acls/include.acl’ and reset the proxy from the web interface (if you change squid.conf directly you will overwrite it if you change anything in the web configuration page)

This will tell Squid to ignore the request, thus it will not send an error, and BAM its working!