Device Manager error code 38

Have a Dell Optiplex sx280.  Having issues sharing a Fujitsu fi-5120c usb scanner between 2 computers.  I have a usb switch I am using to switch between the 2 computers..  The scanner detects fine and the drivers load with no problem after booting.  I scan with no problems and everything is cool.  Switch to PC #2 and same drill, no problems, scanning fine.  The problem occurs when I switch back to PC # 1.  I get a "Windows cannot load the device driver for this hardware because a previous instance of the device driver is still in memory. (Code 38)". in the device manager and my scanning software will not detect the scanner.  I have tried both ac powered switches and line powered switches with no relief.  The same issue occurs if I plug directly into PC #1 with  a straight connect to the scanner and disconnect then reconnect.  The Microsoft knowledge base say to reboot and then run usb troubleshooter.  Rebooting cures the problem but it is not a practical solution as my users switch back and forth repeatedly all day long. ANybody have a cure for this?

Thanks