Chances are that your keyboard needs a good cleaning. Forget about the canned air or microfiber cloths. Those are worthless when it comes to keyboard cleaning. The only way to properly clean a keyboard is in the dishwasher.
Take that keyboard, put a twist tie on the cable, and toss it in the top rack of your dishwasher upside-down. ( Don't put soap in the machine while you do this. Also, run the keyboard by itself.) Run the dishwasher through a regular cycle. When it finishes, shake the water out of it.
You'll want to be certain that the keyboard is completely dry before plugging it back in. Warm the oven up to about 135 degrees. (135 is not hot enough to burn you, so it won't melt the keyboard either.) Place the keyboard on the rack, or on a cookie sheet if it makes you feel better, and set a timer for a few hours.
When your keyboard is completely dry, plug it back in and enjoy your like-new keyboard.
(I wouldn't try this procedure on a fancy mechanical, wireless, or other expensive keyboards. OEM Keyboards like the HP or Dell ones will be fine though.)
