Try re-installing Indesign. If the scripting library dll lost its registration, it could cause all of the scripts to fail.
...wait a minute - are you trying to use this script from the Extendscript Toolkit? If you are, you have to change engines.
Also, if you have more than one version of CS on your system, you need to make sure you use the Extendscript Toolkit that matches the version of your InDesign - in other words, EXTK CS6 for IND CS6.
Another thing to try is to remove the new from your doscript command. I like to wrap mine in a function like this:
//run a script from the CS6 Script Panel Directory (be sure to add the file extension
function RunMyScript(whatscriptname){
app.doScript(File("/C/Program Files (x86)/Adobe/Adobe InDesign CS6/Scripts/Scripts Panel/" + whatscriptname));
}