The enter key on my 9-month-old Acer netbook has stopped working. I'm running a full scan as I type this and I've upgraded to Firefox 4 with no success. Is the key just worn out or is it a software problem?

This is likely a hardware problem, and not related to any of your software.

Keyboards take a lot of abuse and can wear out or get jammed. Crumbs from food, or dust, etc can also get lodged under the key. Fortunately the keys are removable, but you must be careful when removing them from the laptop (the plastic pins that hold them are delicate).

Using a table knife, slide it under the edge of the Enter key. Twist the knife a little to lift up one end. Twist gently until you hear a click as it comes loose. Be gentle and proceed slowly. Some Enter keys have two clips, so you may need to pry up the other end of the key too. Some keys also have a thin metal bar/wire. Notice how this hooks up, because you'll need to put it back together this way.

Look for any hair, crumbs or other items in the space under the key. Also, make sure the plastic/rubber spring-pad is working properly by pushing down on it. If you push on the spring-pad with a pencil (erase end), does the enter key work (open up Notepad or Word while you test this).

If yes, try putting the key back on the way it was. Hopefully everything should work now. If not, make sure you clicked it back in all the way, and that it is seated properly.

If it still doesn't work, there may be other problems with the key, and the best bet is to have a qualified technician take look. Take your system to wherever you bought it, or Best Buy for service.