Cursor goes to arrow regardless of tool selected

[#1]

I've run into a really weird problem.  I might be using the brush or clone stamp.  Suddenly, my brush cursor turns to a standard white arrow and stays there regardless of what tool I select. True whether I use my Cintiq and pen or whether I use a mouse on another monitor.  If I open a new file, the brush will work for a time before it reverts to the white cursor.  My only recourse is to shut down Photoshop and restart, which is annoying as hell.  My efficiency is 100%.  Does anyone know what is happening?  Better yet, how to correct it?

[#2]

I've run into a really weird problem.  I might be using the brush or clone stamp.  Suddenly, my brush cursor turns to a standard white arrow and stays there regardless of what tool I select. True whether I use my Cintiq and pen or whether I use a mouse on another monitor.  If I open a new file, the brush will work for a time before it reverts to the white cursor.  My only recourse is to shut down Photoshop and restart, which is annoying as hell.  My efficiency is 100%.  Does anyone know what is happening?  Better yet, how to correct it?

[#3]

Have you tried resetting your preferences? Will it do that if you are just using the mouse and don't have the Cintiq plugged in?

[#4]

Please indicate system and version

[#5]

Hi there -- 

I am experiencing the same issue with PS 21.2.3, Windows, and a Wacom Intuos.

[#6]

Did you ever find a solution?  I am experiencing the same problem with my Wacom.  I think it is related to using the Space bar to pan the image.