[Users] Claws Mail 3.13 - Windows install issue

[edwardp at openmailbox.org]

There seems to be a problem with the installer for the Windows version 
of Claws Mail.

When I ran the installer, a window eventually appeared, informing me 
that "A version of Claws Mail is already installed on this system. There 
will be no problem and thus overwriting this Version. Do you want to 
continue installing Claws Mail?"

At this time, Claws Mail is /not/ installed on this PC. It had been in 
the past (2014), but not since then.