For RadGrid, after setting EnableKeyboardShortcuts to false, I find the Up/Down keys are also disabled. However, according to your online document below, the Up/Down keys shouldn't be disabled in this case. Do you have the issue?
"To enable this feature you have to set the ClientSettings -> AllowKeyboardNavigation property of the grid to true (it's default value is false). The grid also features an additional property ClientSettings -> KeyboardNavigationSettings -> EnableKeyboardShortcuts which when set to false will disable all keyboard navigation shortcuts except for the Up/Down and Page Up]/Page Down keys. This is done with a view to facilitating the developer if he intends to implement his own scenario if the above-listed keys (with the exceptions mentioned) have been pressed."