keyboard delay when entering data

I have a user that has a dell latitude(D820)that is hooked up to a docking station. The user uses a standard keyboard that would be used with a normal pc setup. The user has been complaining that is a delay or even no keyboard output. This problem does not happen all the time. I know there is a setting in the control panel that you can increase the repeat delay and the repeat rate on the keyboard. I have traded out the keyboard that is uses usb connection and the problem still occurs. Is there anything else I can do or does any one of another solution. Thank you for your help. Markus