Not sure if duplicate since the issue has been raised multiple time during different versions...
1. Installed JDK in D:\Program Files\java\jdk1.7.0
2. Set JAVA_HOME and GRAILS_HOME appropriately in environment variables and path
3. Tried running grails command in cygwin/cmd and get:
"Error opening zip file or JAR manifest missing : D:/Program
Error occurred during initialization of VM
agent library failed to init: instrument"
Workaround: setting the java agent manually... "grails -javaagent:'d:/Program Files/java/jdk1.7.0'"