Android-SDK r17 ruins working projects

Question

I have updated my android-sdk-package from r16 to r17. I have updated the Eclipse ADT-Plugin too.
My project worked perfectly fine with r16 (android-sdk r16 and Eclipse

Answer 1

Sometimes beside closing/re-opening project eclipse restart is necessary to make everything work as planned and expected. Especially if you updated any of component. But of course as CommonsWare mentioned library folder adjustment is mandatory.