I noticed today that one of my machines would not sign in to Skype. Well it turns out that Skype have a major problem at the moment, I noticed only 241,725 users online which is a lot less than the millions normally logged in to Skype.

I hate to think how much revenue they must be losing, and the disruption it is causing people that rely on Skype, which I have found normally very reliable

On Skype's blog they have some details:

UPDATED 14:02 GMT: Some of you may be having problems logging into Skype. Our engineering team has determined that it’s a software issue. We expect this to be resolved within 12 to 24 hours. Meanwhile, you can simply leave your Skype client running and as soon as the issue is resolved, you will be logged in. We apologize for the inconvenience.

Additionally, downloads of Skype have been temporarily disabled. We will make downloads available again as quickly as possible