[User 325245]

I'll have a look. what are those files named ?  

OK, can you try the one in the TEST repo?  

Thanks for the update, I've tried v3.11 and this runs through without any errors and it creates a folder.jpg in each folder.  The only problem is the thumbnail it creates is just an empty black image. The folders are no more than 3 deep, any idea what the problem might be?

thanks, 

Hard to tell... just tested it on my PC, works fine 3 levels... please send me the log...