I posted this also in 2016Shuttle topic, so in case just decided to post here as well...
I found in MeshWizard manual:
[FONT=Arial, Helvetica, sans-serif]I get a crash to desktop with "error 68 Device unavailable" message.
Upon exiting the program, Mesh Wizard creates a CONFIG.TXT file with the settings of your last session.
This error refers to removable drive units or, if you switched computer, it may refer to unexisting drive units.
You can either delete CONFIG.TXT (and lose your custom prefs) or you may try editing it to refer to an existing path.[/FONT]
Maybe paths were changed (I mean file names, folder names) - there are references at the bottom of that CONFIG.TXT file.
If MeshWizard does not find some of those files, referenced, it may show this error.
I think I also had this may years ago, deleting file config.txt in MeshWizard's folder solved this problem.