Unable to update SSMS to latest version: a previous update required a reboot for ODBC driver

SSMS was ignoring the color I'd chosen for Operators (the default color is almost invisible against a black background) so I downloaded the latest version of SSMS to see if this feature was working there. But the update is terminated with the error that a previous update required a reboot for the ODBC driver. But I've rebooted several times since last updating SSMS. How to get past this obstacle?