Use a different usb port.
Remove the sim and sd card before you flash.
Per op, you should shut down after the first flash finishes booting.
With phone off, put it in download mode by holding both up and down volume buttons while attaching usb cable. you should see the download mode display on the phone.
Then flash kk kernal with odin.
Sent via XDA from Captivate GB I897.UCKK4 rooted