Clients affected by the bug are:
Skype 5.10 for Windows Skype 5.8 for Mac Skype 4.0 for Linux Skype 1.2 for Windows Phone
The hot fix will address the following issue outlined by Skype:
Skype client crashes during a Skype IM session, which may in some cases result in the last IM entered or sent prior to the crash being delivered to a different IM contact after the Skype client is rebooted or logged in as a new user.
Full Details of the bug and all details can be found here.