@Pitter,
Did you happen to download the new internet explorer update from Microsoft about 10 days ago?
If not, did any other changes occur on your computer at the time the problem started?
My keyboard shortcuts haven't worked properly for Skype since I did that. The IE update also removed the Skype quick launch icon from my toolbar.
I'm guessing that reinstalling the Skype software will fix the problem but have not yet had the time to try it.