Try using the above options
But this one worked for me.
my JAVA_HOME looked like this
C:\Program Files\Java\jdk1.7.0_21;F:\Software\apache-ant-1.9.4-bin\apache-ant-1.9.4\bin
Only keeping the JAVA path in the JAVA_HOME
Remove any additional path if you had given
C:\Program Files\Java\jdk1.7.0_21