If you upgraded your Probox2 to Android 4.1 last week, you may not have realized that another release has been published since.
The first release of Android 4.1 for Probox2 was ULTIMATE.411.012.11.
Now there's a ULTIMATE.411.012.11.130227 version available from the same link at probox2.com and also from w2comp download section.
The visible changes are the additions of "Google Play Music" and "Google Chrome", and some core apps are updated to their latest version.
Again, thanks to W2COMP.com for the information.