Since the 1.7 release, I seem to be getting leftover backup files. It does not happen every time, but often enough to be noticed. Try to delete but says COM Surrogate has it open. Opening and closing the original file does not clear them out. I have to reboot the PC to be able to delete them.
Not a solution to the root problem but killing all “COM Surrogate” processes in Task Manager should allow you to work around this without having to reboot.
For what it’s worth I’ve often had renegade COM Surrogate processes even before the 1.7 release and haven’t noticed a particular increase in the behavior.