japanese keyboard lag

My Japanese notebook has a Japanese layout keyboard installed. I changed the keyboard type in the control panel to the Japanese driver. However, now I get an awful lag in typing with Vista not registering some of the keys pressed. I have never had this problem before.
For example: i am tryin to write a short paragraph and evrytime thee is a typo, its cos the keyboard is not responding or did not register the key pressed. this happens quie abit. my cu is a centrino 1.73ghz an i hve 1GB ram. the cu usage is from 18% to 25% while typing and thememory usage is 799MB.