Hiya. Edited my post as I found the solution so figured I'd post it here to help others.
If you're finding messenger freezing up and bringing your CPU usage up way high since yesterday then here's a fix.
Nytmare suggested it might be the advertisements which seems to be the culprit.
A couple solutions:
1. "In IE, options, security tab, in the restricted sites list, add rad.msn.com then restart Messenger." - Nytmare
This should work for all versions of messenger and not interfere with msn plus.
Note: this doesn't block msn.com or hotmail or anything like that.
2. Another option for MSN 2012 that has a few extra features would be A-patch. It cleans the messenger up by getting rid of annoying links and blocking all the ads.
You can customize what you want it to do. Real easy to install.
http://apatch.org/downloads/ - the top one will do.
I tried them both out.
Either of these will get rid of your ad freezing problems.
