Why do I get two letter Hs when I tap the key only once?

Q  Sometimes when typing, I look up to see that two Hs have been inserted when I have typed only one. It only happens with the letter H – no other key is affected.

I have even tested it, being sure to press the key only once. There is probably a simple solution, but I do not know where to start. The computer runs Windows 7 Home Premium.
Mark Savege

A  Often, this problem is caused by dirt in the keyboard, which can make keys stick. A key only needs to stick for a moment to result in multiple letters being typed.

In most cases, it is easily fixed by simply prising off the keytop (using the tip of a blunt instrument) and blowing to remove any dirt. We would advise using a can of compressed air for this to avoid any moisture getting into the crevices, but if you’re careful, a puff or two from pursed lips should do the job.

Hopefully this should help but if the problem persists, try reducing the repeat delay (which is the time Windows allows a key to be held down before assuming the user wants another of the same character to be typed).

To do this in Windows 7, click Start followed by Control Panel, then Hardware and Sound followed by Devices and Printers. Now right-click the keyboard’s entry under Devices and choose Keyboard settings from the pop-up menu.

Click to select Speed tab and drag the Character repeat slider a little to the left (towards Longer). Click OK to close the dialogue box and try again.