Check to see if you have the top two variables in your user variables under environment variables: JAVA_HOME and PATH. If not, add these variables with the path to your java location and its bin folder. If it is correct, it should look similar to the picture below.
I figured it out!! It turns out that the Chartboost plugin needs to re-run “setup android SDK” after updating. Weird, though, that the error was so un-descriptive. Thanks again for all your help guys!