If you are not a Skype customer then you probably didn't notice the blip that wiped out Skype connectivity for the better part of 48 hours. For those of us that rely on Skype on a daily basis, losing access was pretty fundamental. Not only do I use it for business, but our home phone is now Skype based too.
The official reason, reported here gives some detail to the issues - all triggered, it seems, by a massive automated Windows update.
The only section of the report I don't agree with is this one: