I still got the same error as described here: "Uncaught Reference Error: Polymer is not defined" caused by IP-change?
But after I uninstalled and reinstalled yeoman, grunt, bower and polymer-generator, fresh initialized Polymer-projects work fine now.
My old Polymer-projects still have the same Error.
I am using the newest versions for all tools mentioned above. (Grunt: 0.4.5, Bower: 1.3.9)
After all it seems like the problem was somehow caused by Polymer.
I switched to the newest version of polymer and included it in my project correctly (I used version 0.0.20131010 before) and the errors disappeared. But there was still nothing to see on the screen.
After a lot of searching, I found that a single closing <template>-Tag was missing in one of my elements.
The only thing for me left to do now is fixing all the compatibility issues.
