Streaming media, downloading files, running a backup – there are all kinds of reasons why you might leave your laptop (or any PC) alone for a while. But if your home has babies, pets or other curious passers-by then that could lead to problems, as even a single stray mouse click or key press could interrupt whatever you’re trying to do.

And that’s where KeyboardLock comes in. Small, portable and entirely free, the program can block keyboard and mouse events on demand, making it a little more difficult for even the most determined dog to affect your system setup. (Unless they hit the power switch, anyway.)

To see how this works, launch KeyboardLock, click Start, and minimise the program. It’s now monitoring the keyboard, and if you type the Lock password (cake, by default, although you can change this from the main dialog to whatever you want) then KeyboardLock will grab future keyboard and mouse click events. Which means you’ll be able to move the mouse cursor, but that’s about it – key presses and mouse clicks will have no effect.

Yes, this really is the entire interface - KeyboardLock is very simple to use

And if you want to restore normal operations, just type the Unlock password (dart, by default), KeyboardLock will release its hooks and your keyboard will be active again.

Plainly this isn’t the most essential of programs. If you simply want to lock a PC then you can always just hold down the Windows key and press L, which works just fine without having to install anything at all.

KeyboardLock does have the advantage of not hiding the current desktop, though, which may be useful in some situations (you’re watching a movie, say, or would just like to glance at the screen occasionally to monitor how some ongoing task is progressing).

Just keep in mind that, while all this worked very well for us, there are some potential issues here. Leave KeyboardLock active on a shared PC, for instance, and someone else might type the lock password accidentally, and forgetting the unlock password could also be a problem. Use the program carefully, and only when necessary.