Let's end this once for all.
You got this problem is because you are using 64bits Eclipse, but your ant target is using 32bit JDK.
It's OK to use 32bit JDK in Eclipse, but you'll have problem when your ant need some GUI prompt, at this point, it will call Eclipse to generate this GUI prompt which is 64 bits, and now we'll have problem.
Solutions:
1. Use 32bit Eclipse
2. For those ant targets which require GUI prompt, change JRE to 64bits JDK.
