[Ken Maltby]

You should not be encountering a need for "reset, retry, reset, retry, ect...". If you
are doing so and it sometimes works, for a given file, then there is really something
wrong.

All e-reading devices have "ebooks that can't be opened", they all are limited to a
particular set of formats that they will work with, they all can only read those among
the supported formats that are constructed in a manner acceptable to the ereader.

The JetBook series seem to be able to handle more formats and file types than many
of the others.

I don't know where you are getting these ebooks that are supposed to be in a format
that your JB can read, but that can't be opened by your JB. If you need to continue
obtaining such ebooks from those sources, you should consider converting them in
Calibre with the output format set (in the preferences) for "JetBooK 5-inch". It is a
quick enough process, that is easy to master.

For instances where the loading is taking so long; you should checkout the "Hourglass
of Death" threads, for how your JB library should be structured. And note that the
embedded graphics of an ebook can be the cause of long loading times. The JB & JBL
function much better with 8-bit grayscale images. The display is only black&white, so
you are loosing nothing by converting the images.

The process of converting the embedded images is not as much of a hassle as you
might expect. (In fact it is harder to explain than to do.)

WinRAR can un-zip most eBook formats into a HTML directory structure. Within that,
you should be able to find the image files.

Any good graphic editing program like the free GIMP2 can change the image into an
8-bit grayscale image. You would replace the image files in the HTML directory
structure, with these changed images, retaining the original file names.

Then Calibre can create a new ebook, in the format of your choice, that will load much
faster, from the HTML structure (There will be a base .html file, you would load into
Calibre). [ You may prefer to re-zip the HTML file structure that you un-zipped, and
load that into Calibre. ]

Luck;
Ken