Update (Aug 17,2013): Testing Samsung Kies on MS Windows 7. The Samsung Kies connects after a while or only intermittently. Please see the comments below for possible solutions.
Samsung mobile phone users are familiar with this error. Kies is a personal computer sync software that enables you manage your Samsung phone, similar to iTunes software for Apple iPhones. Samsung Kies software refuses to connect your device and gives this cryptic message.
Reconnect the device in Samsung Kies (PC Studio) mode. Current connection Mode not supported by Kies
Spent an hour raking my brains, then the obvious solution presented itself. Turn off USB Debugging Mode. You will find this setting under Settings > Applications > Development.
Visual Guide to Android USB Development Settings
Samsung Kies software uses MTP (Media Transfer Protocol) mode to talk to your Android device. Enabling USB debugging setting changes your android device to use USB transfer mode.