Also try disabling all plugins and the other things suggested in the FAQ on issues that happen when reading particular folders. It's possible that the problem isn't synching but is something going wrong when the results of the comparison are displayed.
Ah, unchecking all the default plugins does now allow me to stop Dopus during its synchronising, and does allow ProcMon to run.
But, during the long period (up to 10 minutes) while it reads folders, ProcMon shows it is doing little or nothing other than opening and closing Registry keys.
Bob F.