trackpad goes inactive about 5 seconds

I have a little trouble with the trackpad on my macbook Air 2014

If I use the trackpad continusely, it works every time.

If I do nothing about 5 seconds, the trackpad goes inactive and

I can't move the cursor.

If I click the trackpad or hit any key on the keyboard it

works again. It's very irritating.

Who has the same problem and what is the solution?