If you want to use latest Skype version just add following line to hosts file (C:\Windows\System32\drivers\etc):
127.0.0.1 rad.msn.com 127.0.0.1 live.rads.msn.com 127.0.0.1 ads1.msn.com 127.0.0.1 static.2mdn.net 127.0.0.1 g.msn.com 127.0.0.1 a.ads2.msads.net 127.0.0.1 b.ads2.msads.net 127.0.0.1 ac3.msn.com
Today I received a Skype update that started to show advertisements in chat windows.
This was unacceptable for me, so I decided to downgrade Skype to latest ad-free version, which seems to be 18.104.22.168.
You can download old Skype version without ads from here:
To prevent Skype from updating automatically go to:
Tools -> Options… -> Advanced -> Automatic updates and click “Turn off automatic updates’.