Wierd dynamic highlight only on assembly sections

Using v2020 with Nvidia P400 on Dell Precision 3430.  When I section an assembly, highlighting/selecting is OK until I move a component just slightly.  After that I get all these weird dynamic highlight lines when I go to select faces, etc. (see orange color lines).  Have to do a force-top-assy-rebuild all the time.  Anyone else experience this? Thanks.

SolidworksHardware And Graphics