Hmm Nytmare I think you're right..
It being caused by ads would explain a lot like:
1. Why it happens on both messenger versions
2. Why it doesn't always happen. Keeping the contact list closed would probably avoid the crashes.
3. Why it doesn't happen to some people. Ads are probably region-specific too so people in some places might not get the same ones that cause the crash.
4. Why it happened 100% out of the blue when nothing else was touched.
Hopefully something gets fixed soon.
edit: Fortunately, I've found a solution!
It's called A-patch. Gets rid of the ads in the 2012 version of MSN. Might not work with msn plus, but my messenger is ad-free and it hasn't crashed since I started it after installing the patch.
I think we've come to the cause of the issue.
Not sure if it's worth bothering with, but if we can find which ad is causing it then we could I guess message someone who works with microsoft to inform them of it. Not sure if it's even possible to reach them though considering how big a company they are
edit2: didn't see your post below this one as I hadn't refreshed the page.
but yeah that'd work too.
though I like this a-patch tool because it gets rid of lots of clutter