Ok...
I removed calibre completely. Complete exorcism. Removed all calibre data from AppData/Roaming where it creates a folder and uninstalled both 32 and 64-bit versions. Cleaned temp directory. Emptied Recycle Bin. Restarted.
Downloaded a fresh install that purports to be v 1.37 64 bit from main calibre website.
Installed.
Windows reports that the calibre version installed is 1.36.
Calibre reports that the calibre version installed is 1.36.
Revo reports that the calibre version installed is 1.36.
I went into the install directory. Program Files\Calibre2\.
I found calibre.exe, right-clicked and brought up properties.
Properties reports that it is version 1.36.
I downloaded and installed 1.38 this morning. Now I have 1.38 up and running.
Still don't understand what the problem with 1.37 was.
Thanks to everyone who tried to help.
Maybe things would go better for me if I removed Greenwald from my list of Google Now reminders. Probably been targeted as a dissident or something worse.
40% kidding. If I were a government agency interested in knowing it ALL I would certainly target the e-reader of choice for anyone with even the slightest modicum of intelligence on the internet.