Okay, I give up, I'm gonna swap it..........
it worked fine for a while then I turned off via menu, next time on it had no bookmarks and 3 collection went missing...........so I removed MS and synced it so that I had most of what I wanted on the internal memory.
Booted up okay, looked at a few books, switched off via menu. next switch on, while on start screen it reset itself then rebooted, this time taking 5 books off the reader !
So it either resets during formatting, tkaing collections away, or resets when I place/remove a bookmark taking bookmarks, switch off and on and lose the odd bookmark or place in books, or resets during start-up and loses books.
I admit defeat, time to replace. Hopefully new one will arrive Monday. I need to change it, otherwise I will always wonder if I have a faulty unit, this one just loves to reset.
Thanks for all your help guys, as usual you have been great