Laptop typing issue

i would do a full virus scan without network .

What usually causes this is your palm touches your trackpad as you're typing. Your trackpad interprets this touch as a click, and since the palm has touched the upper-left part of the trackpad (for your left hand), it does a mouse click in the upper-left, which is usually towards the beginning of what you're typing.

Go into the trackpad settings and look for something called palm rejection. Tweak its sensitivity up. This makes it less likely that the trackpad will interpret a large blob (like your palm) as a touch. A small blob (like your finger) will still activate it.

If that doesn't work, look for something about the click activation area. This limits the area which can activate a click to the bottom portion of the trackpad. For most people this is well below the area where their palm touches the trackpad. Your mouse pointer will still move as you type, but since there's no click the cursor won't change position.

As a last resort, you can always turn tap to click off. That's only feasible if your trackpad has a physical click switch. If it's the Apple-copycat style which has no physical click switch and relies entirely on tap to click, then you're stuck and must have it enabled.