My 1.5 yr old Macbook, running OS 10.4.11, has worked flawlessly until last week. Now, several times a day unpredictably, the computer will stop receiving most keyboard input. The trackpad will still move the cursor, but no clicks will register. Function keys are the only things that register. The clock still works. If I press the power button to shut-down, the computer then will accept any presses of the return-key to save open windows during shut down. I have read about a similar-sounding problem affecting Leopard, but users make it clear that it is specific to Leopard. Plus, in those descriptions of keyboard freezing, the computers often unfreeze after a few minutes, or after quitting excel. For my problem, the only solution appears to be restart.