A key does not work it just highlights Edit.

If you live near an Apple Store, make a Genius Bar appointment to have the computer tested. Supposedly there is no charge for testing.

Genius Bar Reservation US

Go to Apple Logo > Systems Prefs > Keyboard > Click on Show Keyboard in Menu bar > Go to menu bar > Show keyboard.

Then press the key that concerns you (for my iMac that is V). If the key you've pressed is highlighted in the keyboard viewer ... then it is working properly ... and the fault is elsewhere.

Significantly, this key is the one that enables you to test for software problems by pressing cmd / V. Read the document below.

Mac OS X: How to start up in single-user or verbose mode and check it out from there.

You have mentioned copying twice. Can you tell us what exactly is being copied.

You also keep saying between c and b. The letter between c and b on a QUERTY type keyboard is v. Is that the letter which is being copied?

Or do you mean that that letter (v or whatever) is being continually repeated?

Could you take and post a screen shot?

Make sure you cover any personal information using Preview. Post the screen shot in a Reply using the camera icon. Copy and paste doesn't work.

Screen shots

Where's menu bar ? My key in middle of r and y no+ working.

You might want to consider starting a new discussion. Since this one is marked solved, less people are likely to look at it. You can link to this one.