What OS are you using?
This is have tried this - this is how I have Kies working on Windows 7 64-bit
- Install latest version of Kies (as of now v126.96.36.19993_82) - it will uninstall older versions
- Disable USB debugging
- Set USB settings to "Samsung Kies" don't use Ask on connection
- Goto home screen of TwLauncher on phone - If you not using TwLauncher (the default launcher) [your using something like LauncherPro etc.], then launch TwLauncher - install Home Switcher if required.
- Plug USB cable directly into PC ie. don't use a USB hub.
- Plug in microUSB cable into phone
Try another PC perhaps?