I will now tell you more about the Skype bug I recently discovered. It's pretty easy to reproduce it.
All you need is a Skype chat conversation that has entries let's say, for the last 15 minutes.
And now you go to your clock time/date of your Windows (haven't tried it for Linux but I guess the result will be the same) and change it 15 minutes to the past.
Now you chat some more! The strange thing you should notice is that your 'new' entries are put between your other chat entries! This happens simply because they are ordered with key the time these entries are made.
So if you are chatting with Skype and decide to play with your clock , you will notice this strange behaviour.
Don't change your clock settings unless you want your chat history scrambled. The Skype folks should document this somewhere.