My keyboard is typing by itself, could there be a ghost in it?

The keyboard on my laptop seems to be typing by itself:

• It sometimes types characters like 134, whether by itself or when I hit certain keys.
• Repeating characters may appear unexpectedly.
• The system volume may change by itself, or windows like the Print dialog or Web browser may appear.

This can happen without any input or as I type, and may occur more often when certain keys are pressed. Sometimes, the keyboard fails to respond altogether. This is happening regardless of the software involved.

Is there a ghost in my keyboard—is my keyboard broken?

A sample of text from the keyboard might look like this (normal QWERTY...ASDF...ZXC... sequence is expected):

QWERTYUIOPASDF)(G@*HKLZXCVBN
QWERTYIOPASDFGL!#ZXCVB13
QWERTYUIOPASDFGHJKLZXCVB!#N
qwertyu41iopasdf19g13h28j113k4113zxcvb4n
qwerty4u1iopasdf0g7h1jklzxcvb13m
qwert13uuuuuuuuuuuuuuuiopasdf87091134ghhhhhhhhhhhhhhhhhhhhhhh13jk13zxcvb14

This question comes up often and the answers are usually the same. This post is meant to provide a definitive, canonical answer for this problem. Feel free to edit the answer to add additional details.

If it is still in warranty, save yourself the hassle and just get it repaired or replaced.

If it is out of warranty, it could be one of a few things and there is no easy way to tell.

1. Malware (unlikely): Test via going to an Ubuntu or similar boot disk and open notepad/command line and see if the same thing happens
2. Loose Connection: Try taking the keyboard and reseating it. A bit of dust may have got on the connector, or it could just be loose. Putting a bit of pressure on the keyboard may be making a short circuit.
3. Bad Keyboard: It’s just faulty, need to replace it.
4. Bad Motherboard: Worst of the worst. A friend had an Acer laptop with a very similar diagnosis, it turned out that the same thing happened even with a new keyboard, but not USB keyboard. So the only thing I could say was the motherboard was faulty.
5. Debris: There might be some debris, like a paperclip or food, stuck under or between the keys. Try prising the keys off and shaking the keyboard upside-down to loosen it.
6. Ghost: Like your title says, there could actually be a ghost in there!