In order to solve the problem, open the Synaptics Pointing Device and navigate to Touchpad Properties > Device Settings > Settings > Palm Enhanced ACM Settings. After that, select the slider, move it to off and save the changes.
If it doesn't work, press Windows + R key combination, type regedit and click OK. Go to HKEY-LOCAL-MACHINE > SOFTWARE > Synaptics > SynTP > Defaults and set the PalmKms entries values to 0. In this way your touch pad will stay disabled 0 seconds after you hit a key from your keyboard.