I bought the above ereader several years ago, and it has worked fine, including when I added ebooks using the Calibre freeware software.
Recently, I started using a 16GB MicroSD card, because I wanted to be able to read some ebooks on more than one device. The Calibre software seems to download the ebooks successfully to the MicroSD card, and the reader always finds them OK the first time - and sometimes more than one time - I try to read them.
However, at some time later, these ebooks just seem to get "lost": the ereader can't find them - even when the PC can see that they are still there - and I have had to re-format the MicroSD and download them again.
The current situation is the worst yet. There were about 17 ebooks on the MicroSD, two downloaded about a week ago - which I read part of the same day - but the next time I powered up the ereader, it just got hung up and didn't even get to the home page. I powered it down, took the MicroSD out, powered it up and all was OK. I looked at the MicroSD via an independent adapter and found that the actual ebook content files had all vanished - the folder they usually live in is now empty - although other "parts" of them - eg the cover images - are still there.
Other attempts to look at the MicroSD with the ereader have had various results, including one where the ereader got "stuck" again, but with the home page showing a few of the missing ebook titles under icons showing "Removing"... and this taking so long that the ereader went into sleep mode before I could look at anything else.
I have studied the User Guide for the ereader, but there's not much help there. I know I can re-format the MicroSD and download the ebooks again, but this is a bore,,, with no guarantee that the same won't happen again.
Has anyone else experienced a similar problem? Or can someone suggest what I may be doing wrong?