Users on Skype's community forums have discovered a bug that renders the app unusable when a message containing a particular string of characters is received. Sending "http://:" without the quotes crashes the instant messaging service, and since the message is stored in your chat history, every time you sign back in, the app crashes again.
In a statement to VentureBeat, Skype acknowledged the existence of the bug:
We are aware of the problem and are working to provide an resolution.
The bug seems to affect Skype for Windows, Android and iOS, but not the Mac client. At this stage, if you have the message in your chat history, you will not be able to use the Skype for Windows app, although the mobile platforms are unaffected so long as you don't receive the message when you're using the Android or iOS clients. A post on the community forum (which has since been removed) offers a workaround for Windows users:
Skype user "Lazymax" notes that you can get around the bug if the person who sent you the characters deletes the "bad" message. If you then install an older version of Skype, you can use it again.
We'll update you once we hear more on the matter.
Thanks Ronnie for the tip!