Try the following, it sounds like a Windows issue and this might
1) Make sure the phone is not connected and Kies Air is off.
2) Uninstall Kies (Control Panel, Uninstall a program or Add/Remove Programs)
3) Reboot and run a CHKDSK (If you don't know how, follow steps 4 - 9, if you know how then skip to 10)
4) Open Windows Explorer, right click on your C drive, select Properties.
5) In the Properties window, select the Tools Tab.
6) Click on the "Check Now" button in the Error-checking section.
7) When the dialog pops up, make sure there is a check beside "Automatically fix file system errors" and click the Start button
8) When another dialog pops up indicating that it can't scan because it is use, click on "Schedule disk check". Click OK on the properties window and reboot your computer.
9) Let the PC scan and fix any errors by not touching the keyboard or mouse when the computer is rebooting. You will see a screen where the disk will be checked.
10) When back in Windows, fully booted and at your desktop, uninstall the Samsung USB drivers that you have installed (Control Panel, Uninstall a program or Add/Remove Program)
11) Delete the Samsung install directory (default is C:\Program Files (x86)\Samsung if installed on a 64bit PC and C:\Program Files\Samsung on a 32bit PC)
12) Reboot for good measure.
13) Download and install the latest version of Kies (includes USB drivers). It can be found here: What's new for Software & Manual SAMSUNG
14) Reboot for good measure.
15) When back in Windows and fully loaded at the Desktop, start Kies and connect your phone making sure your phone is ON.
This should solve the issue, but may not. It will take about 15 minutes to do depending on the speed of your computer, so it is worth a try. Hope this helps.