Když nepomůže přeinstalovat DirectX, tak:
http://forum.skype.com/index.php?showtopic=685963& st=20The issue seems to have started already with Skype 4.2.0.187 from Sept 7, on Windows 7 and XP at least.
Go to http://www.oldapps.com/skype.php and download Skype 4.2.0.169 and you'll probably be fine.
Still waiting for Skype to explain this as it seems to be a widespread problem.