My copy of Chrome has been refusing to print in Google Documents. The print preview doesn't work and I get a message saying that the Chrome PDF Viewer needs to be enabled. When I checked it was already active. I tried disabling and enabling it again, but that did not help. I then enabled the Chrome NaCl plugin and that fixed it. You will find it in the plug in list near to Chrome PDF Viewer. I suspect that this might be because the new preview system runs natively in the browser.
Hope this helps someone else.