Zoom Not Working When Mouse Button Held Down

Hello Forum

I'm having an issue where the zoom tool does not smoothly zoom in when I hold the mouse button down.  If I hold down the mouse button, nothing happens except when I release it and it gives me a set magnification.  The "scrubby" function for zooming is not working either.  I'm using PS CC 2018 on a Windows 10 64-bit PC with 24 GB of RAM, dual displays with an onboard NVIDIA GeForce GTX 645 (1 GB) card.  One monitor is connected via HDMI and the other monitor (for photo editing in PS) is connected via DVI

FYI -- Under Preferences > Performance > Graphics Processor Settings there is nothing listed by "Detected Graphics Processor" and the "Use Graphics Processor" is grayed out.

Any help would be appreciated.

Thanks

DS