In the past, I've always on into Config.groovy and changed this line to false:
grails.enable.native2ascii = true
Now, I've found a way to make sure the error does not show up at all.
Copy the tools.jar file from the JDKPATH/lib directory to the JREPATH/lib/ext directory.
copy %Java_Home%/lib/tools.jar to %Java_Home%/jre/lib/ext/tools.jar fixed this problem..
Thanks to grailslog!