There is a bug in Zorin OS 5 Release Candidate with Google Chrome not launching from the taskbar icon. We are aware of this problem and it will be fixed in the final version. Currently you can get it to work by right clicking the icon in the taskbar and selecting unpin application. Then open Google Chrome from the start menu, right click on the icon in the taskbar and select pin application.
There is also an issue with window previews being faded. This is caused by a bug in the latest version of Compiz and we hope that it will be fixed soon.