In few instances reported so far, the Thumbs Rating values have become invalid, showing million or billion high ratings. So far, we were unable to find the cause of the problem, but it was caused by something in the early 3.x versions of the plugin. To fix this issue, you need to recalculate the Thumbs Rating, and the ratings will be fixed.
To do that, open the Rating System plugin admin menu, go to Tools and open Recalculate Data tool. Make sure to read all the provided information there. Find the Thumbs Rating box, and enable recalculation for it. Click the Recalculate button, and wait for the process to run, you will see the progress information. Once it is done, check the posts that had invalid ratings to confirm that the problem has been solved.
Also, it is recommended to update plugin to the latest available version before doing this.