Hi guys, thanks for the useful hints! I have checked the setup of the audio settings, finding that the device type was set to MME. I have chenged it to WAS, and now the program works fine! I have also verified that the audio was set to WAS on the desktop PC (probably this is the default setting when the software is installed?).
I guess that the updating of Windows 10 has in someway changed the setting of the audio device on the Laptop.
I have also changed the setting of the Real Tracks disabling the option to speed up the generation of Real Tracks, just to be sure that this option will not contribute to the problems of the audio on my (not so fast) Laptop PC.