Sorry looks as if I posted the wrong forum but in case anyone else has the same problem.
I solved the issue-
- uninstalled Displaylink software completely again using Revo Uninstaller advanced settings
- Checked and it was cleared from the registry
- I then went in an manually deleted the old Toshiba Displaylink monitor from the registry (serious caution if you do this- I almost deleted some other important Toshiba items)
- Made sure the ASUS software was also gone.
- Then reinstalled Display link software- had the monitor connected to a powered USB3 and it appeared to install properly- rebooted.
- Same thing- just for grins I decided to try the one non powered USB3 again.
That worked-yippee
BTW - in the course of things I went to back up some files before creating havoc .
I had " USB selective Suspend" set to Disabled per the troubleshooting. I discovered that doing that made it impossible to use a USB drive attached for backup- went back restored that to enable and the USB drive was fine.