Mac laptop rotate view problem

Grasshopper
1

After leaving Rhino on (just not quitting the software, even without any window open) for a moment (>= 1hr), I notice that I lose the ability to two-finger-drag to rotate the viewing angle. Instead, I must click down on the trackpad for it to work. (Sometimes, the program confuses two-finger-move-without-clicking-down for zoom too) I am using a very old machine but my friend who has the new one from last year also get the same problem.