spring - failed to create java virtual machine error in springsource tool?

I have downloaded springsource tool. But on install, it is giving me error "failed to create java virtual machine". Can anyone suggest me some solution?

This is my sts.ini

-startup
plugins/org.eclipse.equinox.launcher_1.2.0.v20110502.jar

--launcher.library
plugins/org.eclipse.equinox.launcher.win32.win32.x86_1.1.100.v20110502

-product
com.springsource.sts.ide

--launcher.defaultAction
openFile

--launcher.XXMaxPermSize
384M
-vm C:\Program Files\Java\jdk1.6.0\bin\javaw.exe
-vmargs

-Dosgi.requiredJavaVersion=1.5

-Xmn128m
-Xms256m

-Xmx768m

-Xss1m
-XX:PermSize=128m
-XX:MaxPermSize=384m