calibre 3.0 and 3.1 "disk not found"

Getting "There is no disk in the drive. Please insert a disk into [drivespec]" error on start-up on Windows 7 Pro 64-bit with Calibre v3.0 Portable.

[IMG]e:\jjd\crash.jpg[/IMG]

Portable installs fine and starts up no problem. When shutting Calibre v.3.0 Portable down (successfully) and subsequently restarting Calibre v.3.0 Portable, I get pop-up dialog error box:
"calibre.exe - No Disk", "There is no disk in the drive. Please insert a disk into [drivespec]"

with options to Cancel/Try Again/Continue, none of which work. I have to kill both the Process (calibre.exe *32) & calibre.exe Application from the Task Manager to let me get out.

I've tried tried installs multiple times, and always starts initially fine from the end of the installation process. After exiting the post-install start-up, always get the error.

I then reinstall v.2.85.1 Portable, and no issues occur, all works fine.

When v.3.1.1 Portable released I tried again; same results as the v.3.0 Portable ...exactly. 2nd start fails in exact same manner.

Went back to v.2.85.1 Portable, and works fine.

Running this from Glyph Atom portable drive (275GB SSD, USB-C 3.1, Gen 2)....runs Calibre Portable great, normally.

Any help appreciated!

Thanks.

JEff