m240: Playback position/resume function problem with audiobooks

My daughter has an m240 and uses it mainly for audiobooks (from audible.co.uk). It remembers the playback position which is great when she turns it off in the middle of a book, it resumes from there next time. However, when it gets to the end, the playback position gets stuck at the end, and she cannot then start again at the beginning. Bit of a problem when she falls asleep, but it carries on to the end and then she can’t listen to the rest of the story! The only way round this that we’ve found so far is to delete the book file and reload it - obviously no use when we’re away from home.

I don’t know if this is somehow an audible.co.uk problem (have asked there too) or an m240 problem - if the latter, any tips on how to sort it out?