I have seen many Galaxys with this problem. Even my own when I first got it over a year ago. Firstly got to smansung support and choose your model of phone then go to the downloads for your model of smartphone.

Uninstall the old kies and re-install the new. Do not connect your galaxy smartphone into a Card Reader USB port but try the front panel usb is you have one if not then it would have to be the rear ports.

Ok, next it to make sure your smartprone is not going to go into the password lock or standby screen so you will need to turn this off in settings and security. Also turn of Wi-Fi if you have it connected wireless.

Before this next step I strongly recomend you have a MicroSD memory card fitted in the phone and you have backed up all to your card. To check then switch off the phone and open the back, you will see a card which is tiny fitted in the left middle side just about the battery.

If you happy you have got a back-up to your memory card then proceed and connect your galaxy via the USB cable. It must be the cable for your phone.

Hopefully your phone will register with the computer/laptop and the first thing that might happen is it will want to update the firmware for your phone.

If you plan to carry out this firmware for your phone and it fails then it will corrupt your phone setting and you will have to put the old firmware back using the kies recovery firmware tool in the menus

The firmware update usually in most cases fixies connection issues and problems when backing up your phone data to the machine and also can fix other pain problems.

You can opt out of updating the firmware and proceed to make a backup to you machine. Make sure also as it will help that your machine/laptop does not go on screen saver and especially standby while working with it.

If there are any other updates like Adobe, Java windows updates wanting to be updated then get these done so the windows doesn't get dragged down.

Good Luck