64bit Launch Eclipse Error Out "jvm terminated.Exit code=-1"

I got a very strange error when launch Eclipse 64 bit after reinstalling the Windows 7 64bit. Then I checked the java version, it's 64 bit. Google this error message, it said 64bit eclipse requires 64 JVM.

Try to specify the JVM location by adding the launch parameter -vm "I:\Program Files\Java\jdk1.6.0_18\bin\javaw.exe", it works. Not sure what's the real problem.Please let me know if you find the root cause.