Lately skype started displaying an advertisment for itself whenever you open a new chat window. When it does (with some delay), it steals the focus from the textbox.
So you start entering your message, and discover, that only half of it was entered because of the nasty popup.

Here’s how to get rid of:

1) Open  ‘Internet Options’ (not from skype, but out of windows or IE)

2) Goto ‘Security’ tab, and select ‘Restricted Sites’

3) now click the ‘Sites’ button below, and enter the following URL: https://apps.skype.com/

And voila: focus stealing ad be gone !