Unfortunately it didn't work for me, and it took forever digging up a fix in an unrelated article. The problem wasn't ownership, it was the setuid bit. In the Terminal, type:
% cd /System/Library/CoreServices/ClassicThen go inside the ClassicStartup.app:
% cd "Classic Startup.app"/Contents/MacOSand type % sudo chmod ug+s *then type
% chown root *And your Classic should work again.

