And an observation from me since I've just spent 30 mins troubleshooting and it makes no sense for everyone else to have to as well...
Most addons have either been updated or the old versions work fine when you set "load out of date addons" to be true. SpamMeNot causes random chat problems (can't shift-click a name to get details, random channels seem to become invisible) so I've got it disabled for now.