I have a apple usb wired keyboard and thought that was the problem but it wasn't. After attempting to press random keys it stopped but it came back. The computer began to also produce a repeated alarm noise. No matter what I would do it would not stop.
I have a new Maverick software updated MacBook 13 250ssd 8gRam and while going about my business the number 5 was constantly phantomly pressed. Today I experienced this abnormal behavior. You must press this key combination before the gray screen appears. You will need to hold these keys down simultaneously in step 4. If you have AppleCare give them a call and they can also help you troubleshoot the problem and if necessary arrange a replacement keyboard. If the problem persists you may have a keyboard with a stuck key, in that case it's covered by warranty. Try doing a SMC reset and PRAM reset, you may need to do each 2x.
